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Author |
van Duijn, F.; Osca, J.; Sorée, B. |
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Title |
Skyrmion elongation, duplication, and rotation by spin-transfer torque under spatially varying spin current |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
104 |
Issue |
9 |
Pages |
094426 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The effect of the spatially varying spin current on a skyrmion is numerically investigated. It is shown that an inhomogeneous current density induces an elongation of the skyrmion. This elongation can be controlled using current pulses of different strength and duration. Long current pulses lead to a splitting that forms two replicas of the initial skyrmion while for short pulses the elongated skyrmion relaxes back to its initial circular state through rotation in the MHz-GHz frequency range. The frequency is dependent on the strength of the damping coefficient. |
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Wos |
000704236000002 |
Publication Date |
2021-09-21 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3.836 |
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Call Number |
UA @ admin @ c:irua:182467 |
Serial |
7018 |
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Permanent link to this record |
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Author |
Kao, K.-H.; Verhulst, A.S.; Vandenberghe, W.G.; Sorée, B.; Magnus, W.; Leonelli, D.; Groeseneken, G.; De Meyer, K. |
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Title |
Optimization of gate-on-source-only tunnel FETs with counter-doped pockets |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
IEEE transactions on electron devices |
Abbreviated Journal |
Ieee T Electron Dev |
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Volume |
59 |
Issue |
8 |
Pages |
2070-2077 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We investigate a promising tunnel FET configuration having a gate on the source only, which is simultaneously exhibiting a steeper subthreshold slope and a higher ON-current than the lateral tunneling configuration with a gate on the channel. Our analysis is performed based on a recently developed 2-D quantum-mechanical simulator calculating band-to-band tunneling and including quantum confinement (QC). It is shown that the two disadvantages of the structure, namely, the sensitivity to gate alignment and the physical oxide thickness, are mitigated by placing a counter-doped parallel pocket underneath the gate-source overlap. The pocket also significantly reduces the field-induced QC. The findings are illustrated with all-Si and all-Ge gate-on-source-only tunnel field-effect transistor simulations. |
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Thesis |
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Place of Publication |
New York, N.Y. |
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Language |
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Wos |
000306920200011 |
Publication Date |
2012-06-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0018-9383;1557-9646; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.605 |
Times cited |
72 |
Open Access |
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Notes |
; Manuscript received February 17, 2012; revised May 7, 2012; accepted May 11, 2012. Date of publication June 26, 2012; date of current version July 19, 2012. This work was supported by the Interuniversity Microelectronics Center's Industrial Affiliation Program. The work of W. G. Vandenberghe was supported by the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen) through a Ph.D. stipend. The review of this paper was arranged by Editor H. S. Momose. ; |
Approved |
Most recent IF: 2.605; 2012 IF: 2.062 |
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Call Number |
UA @ lucian @ c:irua:100820 |
Serial |
2487 |
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Permanent link to this record |
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Author |
Zhang, Y.; Fischetti, M.V.; Sorée, B.; Magnus, W.; Heyns, M.; Meuris, M. |
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Title |
Physical modeling of strain-dependent hole mobility in Ge p-channel inversion layers |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
106 |
Issue |
8 |
Pages |
083704,1-083704,9 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We present comprehensive calculations of the low-field hole mobility in Ge p-channel inversion layers with SiO2 insulator using a six-band k·p band-structure model. The cases of relaxed, biaxially, and uniaxially (both tensily and compressively) strained Ge are studied employing an efficient self-consistent methodmaking use of a nonuniform spatial mesh and of the Broyden second methodto solve the coupled envelope-wave function k·p and Poisson equations. The hole mobility is computed using the KuboGreenwood formalism accounting for nonpolar hole-phonon scattering and scattering with interfacial roughness. Different approximations to handle dielectric screening are also investigated. As our main result, we find a large enhancement (up to a factor of 10 with respect to Si) of the mobility in the case of uniaxial compressive stress similarly to the well-known case of Si. Comparison with experimental data shows overall qualitative agreement but with significant deviations due mainly to the unknown morphology of the rough Ge-insulator interface, to additional scattering with surface optical phonon from the high- insulator, to Coulomb scattering interface traps or oxide chargesignored in our calculationsand to different channel structures employed. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000271358100050 |
Publication Date |
2009-10-20 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
29 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.068; 2009 IF: 2.072 |
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Call Number |
UA @ lucian @ c:irua:80137 |
Serial |
2617 |
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Permanent link to this record |
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Author |
Pourghaderi, M.A.; Magnus, W.; Sorée, B.; Meuris, M.; de Meyer, K.; Heyns, M. |
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Title |
Tunneling-lifetime model for metal-oxide-semiconductor structures |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Physical review : B : solid state |
Abbreviated Journal |
Phys Rev B |
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Volume |
80 |
Issue |
8 |
Pages |
085315,1-085315,10 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
In this paper we investigate the basic physics of charge carriers (electrons) leaking out of the inversion layer of a metal-oxide-semiconductor capacitor with a biased gate. In particular, we treat the gate leakage current as resulting from two combined processes: (1) the time-dependent decay of electron wave packets representing the inversion-layer charge and (2) the local generation of new electrons replacing those that have leaked away. As a result, the gate current simply emerges as the ratio of the total charge in the inversion layer to the tunneling lifetime. The latter is extracted from the quantum dynamics of the decaying wave packets, while the generation rate is incorporated as a phenomenological source term in the continuity equation. Not only do the gate currents calculated with this model agree very well with experiment, the model also provides an onset to solve the paradox of the current-free bound states representing the resonances of the Schrödinger equation that governs the fully coupled metal-oxide-semiconductor system. |
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Place of Publication |
Lancaster, Pa |
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Wos |
000269639300076 |
Publication Date |
2009-08-21 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
2 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2009 IF: 3.475 |
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Call Number |
UA @ lucian @ c:irua:78294 |
Serial |
3763 |
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Permanent link to this record |
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Author |
Bizindavyi, J.; Verhulst, A.S.; Sorée, B.; Groeseneken, G. |
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Title |
Signature of ballistic band-tail tunneling current in tunnel FET |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Ieee Transactions On Electron Devices |
Abbreviated Journal |
Ieee T Electron Dev |
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Volume |
67 |
Issue |
8 |
Pages |
3486-3491 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
To improve the interpretation of the tunnel field-effect transistor (TFET) measurements, we theoretically identify the signatures of the ballistic band-tail (BT) tunneling (BTT) current in the transfer and output characteristics of the TFETs. In particular, we demonstrate that the temperature dependence of a BTT-dominated subthreshold swing (SS) is in agreement with the reported experimental results. We explain how the temperature dependence of the output characteristics can be used to distinguish between a current dominated by BTT and a current dominated by trap-assisted tunneling. Finally, we propose an expression that relates the energetic extension of the quasi-extended BT states in the bandgap to the onset voltage for tunneling. |
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Wos |
000552976100072 |
Publication Date |
2020-07-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0018-9383 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.1 |
Times cited |
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Open Access |
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Notes |
; This work was supported by imec's Industrial Affiliation Program. ; |
Approved |
Most recent IF: 3.1; 2020 IF: 2.605 |
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Call Number |
UA @ admin @ c:irua:171189 |
Serial |
6601 |
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Permanent link to this record |
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Author |
Contino, A.; Ciofi, I.; Wu, X.; Asselberghs, I.; Celano, U.; Wilson, C.J.; Tokei, Z.; Groeseneken, G.; Sorée, B. |
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Title |
Modeling of edge scattering in graphene interconnects |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
IEEE electron device letters |
Abbreviated Journal |
Ieee Electr Device L |
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Volume |
39 |
Issue |
7 |
Pages |
1085-1088 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Graphene interconnects are being considered as a promising candidate for beyond CMOS applications, thanks to the intrinsic higher carrier mobility, lower aspect ratio and better reliability with respect to conventional Cu damascene interconnects. However, similarly to Cu, line edge roughness can seriously affect graphene resistance, something which must be taken into account when evaluating the related performance benefits. In this letter, we present a model for assessing the impact of edge scattering on the resistance of graphene interconnects. Our model allows the evaluation of the total mean free path in graphene lines as a function of graphene width, diffusive scattering probability and edge roughness standard deviation and autocorrelation length. We compare our model with other models from literature by benchmarking them using the same set of experimental data. We show that, as opposed to the considered models from literature, our model is capable to describe the mobility drop with scaling caused by significantly rough edges. |
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Wos |
000437087400041 |
Publication Date |
2018-05-07 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0741-3106 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.048 |
Times cited |
1 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 3.048 |
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Call Number |
UA @ lucian @ c:irua:152465UA @ admin @ c:irua:152465 |
Serial |
5114 |
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Permanent link to this record |
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Author |
Moors, K.; Sorée, B.; Tokei, Z.; Magnus, W. |
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Title |
Resistivity scaling and electron relaxation times in metallic nanowires |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
116 |
Issue |
6 |
Pages |
063714 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We study the resistivity scaling in nanometer-sized metallic wires due to surface roughness and grain-boundaries, currently the main cause of electron scattering in nanoscaled interconnects. The resistivity has been obtained with the Boltzmann transport equation, adopting the relaxation time approximation of the distribution function and the effective mass approximation for the conducting electrons. The relaxation times are calculated exactly, using Fermi's golden rule, resulting in a correct relaxation time for every sub-band state contributing to the transport. In general, the relaxation time strongly depends on the sub-band state, something that remained unclear with the methods of previous work. The resistivity scaling is obtained for different roughness and grain-boundary properties, showing large differences in scaling behavior and relaxation times. Our model clearly indicates that the resistivity is dominated by grain-boundary scattering, easily surpassing the surface roughness contribution by a factor of 10. (C) 2014 AIP Publishing LLC. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000341179400036 |
Publication Date |
2014-08-15 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979;1089-7550; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
17 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 2.068; 2014 IF: 2.183 |
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Call Number |
UA @ lucian @ c:irua:119260 |
Serial |
2882 |
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Permanent link to this record |
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Author |
Raymenants, E.; Bultynck, O.; Wan, D.; Devolder, T.; Garello, K.; Souriau, L.; Thiam, A.; Tsvetanova, D.; Canvel, Y.; Nikonov, D.E.; Young, I.A.; Heyns, M.; Sorée, B.; Asselberghs, I.; Radu, I.; Couet, S.; Nguyen, V.D. |
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Title |
Nanoscale domain wall devices with magnetic tunnel junction read and write |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Nature Electronics |
Abbreviated Journal |
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Volume |
4 |
Issue |
6 |
Pages |
392-398 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The manipulation of fast domain wall motion in magnetic nanostructures could form the basis of novel magnetic memory and logic devices. However, current approaches for reading and writing domain walls require external magnetic fields, or are based on conventional magnetic tunnel junctions (MTJs) that are not compatible with high-speed domain wall motion. Here we report domain wall devices based on perpendicular MTJs that offer electrical read and write, and fast domain wall motion via spin-orbit torque. The devices have a hybrid free layer design that consists of platinum/cobalt (Pt/Co) or a synthetic antiferromagnet (Pt/Co/Ru/Co) into the free layer of conventional MTJs. We show that our devices can achieve good tunnelling magnetoresistance readout and efficient spin-transfer torque writing that is comparable to current magnetic random-access memory technology, as well as domain wall depinning efficiency that is similar to stand-alone materials. We also show that a domain wall conduit based on a synthetic antiferromagnet offers the potential for reliable domain wall motion and faster write speed compared with a device based on Pt/Co. Domain wall devices based on perpendicular magnetic tunnel junctions with a hybrid free layer design can offer electrical read and write, and fast domain wall motion driven via spin-orbit torque. |
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Place of Publication |
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Wos |
000665011500005 |
Publication Date |
2021-06-23 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2520-1131 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:179673 |
Serial |
7003 |
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Permanent link to this record |
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Author |
Sethu, K.K.V.; Ghosh, S.; Couet, S.; Swerts, J.; Sorée, B.; De Boeck, J.; Kar, G.S.; Garello, K. |
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Title |
Optimization of tungsten beta-phase window for spin-orbit-torque magnetic random-access memory |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical Review Applied |
Abbreviated Journal |
Phys Rev Appl |
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Volume |
16 |
Issue |
6 |
Pages |
064009 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Switching induced by spin-orbit torque (SOT) is being vigorously explored, as it allows the control of magnetization using an in-plane current, which enables a three-terminal magnetic-tunnel-junction geometry with isolated read and write paths. This significantly improves the device endurance and the read stability, and allows reliable subnanosecond switching. Tungsten in the beta phase, beta-W, has the largest reported antidamping SOT charge-to-spin conversion ratio (theta(AD) approximate to -60%) for heavy metals. However, beta-W has a limitation when one is aiming for reliable technology integration: the beta phase is limited to a thickness of a few nanometers and enters the alpha phase above 4 nm in our samples when industry-relevant deposition tools are used. Here, we report our approach to extending the range of beta-W, while simultaneously improving the SOT efficiency by introducing N and O doping of W. Resistivity and XRD measurements confirm the extension of the beta phase from 4 nm to more than 10 nm, and transport characterization shows an effective SOT efficiency larger than -44.4% (reaching approximately -60% for the bulk contribution). In addition, we demonstrate the possibility of controlling and enhancing the perpendicular magnetic anisotropy of a storage layer (Co-Fe-B). Further, we integrate the optimized W(O, N) into SOT magnetic random-access memory (SOT-MRAM) devices and project that, for the same thickness of SOT material, the switching current decreases by 25% in optimized W(O, N) compared with our standard W. Our results open the path to using and further optimizing W for integration of SOT-MRAM technology. |
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Place of Publication |
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Wos |
000729005800002 |
Publication Date |
2021-12-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2331-7019 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.808 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 4.808 |
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Call Number |
UA @ admin @ c:irua:184832 |
Serial |
7007 |
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Permanent link to this record |
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Author |
Doevenspeck, J.; Zografos, O.; Gurunarayanan, S.; Lauwereins, R.; Raghavan, P.; Sorée, B. |
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Title |
Design and simulation of plasmonic interference-based majority gate |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
AIP advances |
Abbreviated Journal |
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Volume |
7 |
Issue |
6 |
Pages |
065116 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Major obstacles in current CMOS technology, such as the interconnect bottleneck and thermal heat management, can be overcome by employing subwavelength-scaled light in plasmonic waveguides and devices. In this work, a plasmonic structure that implements the majority (MAJ) gate function is designed and thoroughly studied through simulations. The structure consists of three merging waveguides, serving as the MAJ gate inputs. The information of the logic signals is encoded in the phase of transmitted surface plasmon polaritons (SPP). SPPs are excited at all three inputs and the phase of the output SPP is determined by theMAJof the input phases. The operating dimensions are identified and the functionality is verified for all input combinations. This is the first reported simulation of a plasmonic MAJ gate and thus contributes to the field of optical computing at the nanoscale. (C) 2017 Author(s). |
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Wos |
000404621200036 |
Publication Date |
2017-06-23 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2158-3226 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:152632 |
Serial |
7764 |
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Permanent link to this record |
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Author |
Pourghaderi, M.A.; Magnus, W.; Sorée, B.; Meuris, M.; de Meyer, K.; Heyns, M. |
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Title |
Ballistic current in metal-oxide-semiconductor field-effect transistors: the role of device topology |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
106 |
Issue |
5 |
Pages |
053702,1-053702,8 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
In this study we investigate the effect of device topology on the ballistic current in n-channel metal-oxide-semiconductor field-effect transistors. Comparison of the nanoscale planar and double-gate devices reveals that, down to a certain thickness of the double gate film, the ballistic current flowing in the double gate device is twice as large compared to its planar counterpart. On the other hand, further thinning of the film beyond this threshold is found to change noticeably the confinement and transport characteristics, which are strongly depending on the film material and the surface orientation. For double gate Ge and Si devices there exists a critical film thickness below which the transverse gate field is no longer effectively screened by the inversion layer electron gas and mutual inversion of the two gates is turned on. In the case of GaAs and other similar IIIV compounds, a decrease in the film thickness may drastically change the occupation of the L-valleys and therefore amend the transport properties. The simulation results show that, in both cases, the ballistic current and the transconductance are considerably enhanced. |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000269850300052 |
Publication Date |
2009-09-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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|
ISSN |
0021-8979; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
2.068 |
Times cited |
3 |
Open Access |
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|
Notes |
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Approved |
Most recent IF: 2.068; 2009 IF: 2.072 |
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Call Number |
UA @ lucian @ c:irua:79744 |
Serial |
214 |
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Permanent link to this record |
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Author |
Verreck, D.; Van de Put, M.; Sorée, B.; Verhulst, A.S.; Magnus, W.; Vandenberghe, W.G.; Collaert, N.; Thean, A.; Groeseneken, G. |
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Title |
Quantum mechanical solver for confined heterostructure tunnel field-effect transistors |
Type |
A1 Journal article |
|
Year |
2014 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
|
|
Volume |
115 |
Issue |
5 |
Pages |
053706-53708 |
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|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Heterostructure tunnel field-effect transistors (HTFET) are promising candidates for low-power applications in future technology nodes, as they are predicted to offer high on-currents, combined with a sub-60 mV/dec subthreshold swing. However, the effects of important quantum mechanical phenomena like size confinement at the heterojunction are not well understood, due to the theoretical and computational difficulties in modeling realistic heterostructures. We therefore present a ballistic quantum transport formalism, combining a novel envelope function approach for semiconductor heterostructures with the multiband quantum transmitting boundary method, which we extend to 2D potentials. We demonstrate an implementation of a 2-band version of the formalism and apply it to study confinement in realistic heterostructure diodes and p-n-i-n HTFETs. For the diodes, both transmission probabilities and current densities are found to decrease with stronger confinement. For the p-n-i-n HTFETs, the improved gate control is found to counteract the deterioration due to confinement. (C) 2014 AIP Publishing LLC. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000331645900040 |
Publication Date |
2014-02-05 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979;1089-7550; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
2.068 |
Times cited |
15 |
Open Access |
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|
Notes |
; D. Verreck acknowledges the support of a Ph.D. stipend from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen). This work was supported by imec's Industrial Affiliation Program. ; |
Approved |
Most recent IF: 2.068; 2014 IF: 2.183 |
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Call Number |
UA @ lucian @ c:irua:115825 |
Serial |
2780 |
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Permanent link to this record |
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Author |
Nourbakhsh, A.; Cantoro, M.; Klekachev, A.; Clemente, F.; Sorée, B.; van der Veen, M.H.; Vosch, T.; Stesmans, A.; Sels, B.; de Gendt, S. |
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Title |
Tuning the Fermi level of SiO2-supported single-layer graphene by thermal annealing |
Type |
A1 Journal article |
|
Year |
2010 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
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|
Volume |
114 |
Issue |
5 |
Pages |
6894-6900 |
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Keywords |
A1 Journal article; Electron Microscopy for Materials Science (EMAT); |
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Abstract |
The effects of thermal annealing in inert Ar gas atmosphere of SiO2-supported, exfoliated single-layer graphene are investigated in this work. A systematic, reproducible change in the electronic properties of graphene is observed after annealing. The most prominent Raman features in graphene, the G and 2D peaks, change in accord to what is expected in the case of hole doping. The results of electrical characterization performed on annealed, back-gated field-effect graphene devices show that the neutrality point voltage VNP increases monotonically with the annealing temperature, confirming the occurrence of excess hole accumulation. No degradation of the structural properties of graphene is observed after annealing at temperatures as high as 400 °C. Thermal annealing of single-layer graphene in controlled Ar atmosphere can therefore be considered a technique to reproducibly modify the electronic structure of graphene by tuning its Fermi level. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000276562500002 |
Publication Date |
2010-03-26 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
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ISSN |
1932-7447;1932-7455; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
4.536 |
Times cited |
54 |
Open Access |
|
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Notes |
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Approved |
Most recent IF: 4.536; 2010 IF: 4.524 |
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Call Number |
UA @ lucian @ c:irua:89508 |
Serial |
3757 |
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Permanent link to this record |
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Author |
Vandenberghe, W.; Sorée, B.; Magnus, W.; Groeseneken, G. |
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Title |
Zener tunneling in semiconductors under nonuniform electric fields |
Type |
A1 Journal article |
|
Year |
2010 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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|
Volume |
107 |
Issue |
5 |
Pages |
054520,1-054520,7 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Recently, a renewed interest in Zener tunneling has arisen because of its increasing impact on semiconductor device performance at nanometer dimensions. In this paper we evaluate the tunnel probability under the action of a nonuniform electric field using a two-band model and arrive at significant deviations from the commonly used Kanes model, valid for weak uniform fields only. A threshold on the junction bias where Kanes model for Zener tunneling breaks down is determined. Comparison with Kanes model particularly shows that our calculation yields a higher tunnel probability for intermediate electric fields and a lower tunnel probability for high electric fields. When performing a current calculation comparing to the WKB approximation for the case of an abrupt p-n junction significant differences concerning the shape of the I-V curve are demonstrated. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000275657500136 |
Publication Date |
2010-03-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
22 |
Open Access |
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Notes |
; William Vandenberghe gratefully acknowledges the support of a Ph. D. stipend from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen). These authors acknowledge the support from IMEC's Industrial Affiliation Program and the authors would like to thank Anne Verhulst for useful comments. ; |
Approved |
Most recent IF: 2.068; 2010 IF: 2.079 |
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Call Number |
UA @ lucian @ c:irua:82450 |
Serial |
3929 |
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Permanent link to this record |
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Author |
Zografos, O.; Dutta, S.; Manfrini, M.; Vaysset, A.; Sorée, B.; Naeemi, A.; Raghavan, P.; Lauwereins, R.; Radu, I.P. |
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Title |
Non-volatile spin wave majority gate at the nanoscale |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
AIP advances
T2 – 61st Annual Conference on Magnetism and Magnetic Materials (MMM), OCT 31-NOV 04, 2016, New Orleans, LA |
Abbreviated Journal |
Aip Adv |
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Volume |
7 |
Issue |
5 |
Pages |
056020 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
A spin wave majority fork-like structure with feature size of 40 nm, is presented and investigated, through micromagnetic simulations. The structure consists of three merging out-of-plane magnetization spin wave buses and four magneto-electric cells serving as three inputs and an output. The information of the logic signals is encoded in the phase of the transmitted spin waves and subsequently stored as direction of magnetization of the magneto-electric cells upon detection. The minimum dimensions of the structure that produce an operational majority gate are identified. For all input combinations, the detection scheme employed manages to capture the majority phase result of the spin wave interference and ignore all reflection effects induced by the geometry of the structure. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
Amer inst physics |
Place of Publication |
Melville |
Editor |
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Language |
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Wos |
000402797100177 |
Publication Date |
2017-02-06 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2158-3226 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.568 |
Times cited |
13 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 1.568 |
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Call Number |
UA @ lucian @ c:irua:144288 |
Serial |
4673 |
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Permanent link to this record |
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Author |
Kenawy, A.; Magnus, W.; Sorée, B. |
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Title |
Flux quantization and Aharonov-Bohm effect in superconducting rings |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
Journal of superconductivity and novel magnetism |
Abbreviated Journal |
J Supercond Nov Magn |
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Volume |
31 |
Issue |
5 |
Pages |
1351-1357 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Superconductivity is a macroscopic coherent state exhibiting various quantum phenomena such as magnetic flux quantization. When a superconducting ring is placed in a magnetic field, a current flows to expel the field from the ring and to ensure that the enclosed flux is an integer multiple of h/(2|e|). Although the quantization of magnetic flux in ring structures is extensively studied in literature, the applied magnetic field is typically assumed to be homogeneous, implicitly implying an interplay between field expulsion and flux quantization. Here, we propose to decouple these two effects by employing an Aharonov-Bohm-like structure where the superconducting ring is threaded by a magnetic core (to which the applied field is confined). Although the magnetic field vanishes inside the ring, the formation of vortices takes place, corresponding to a change in the flux state of the ring. The time evolution of the density of superconducting electrons is studied using the time-dependent Ginzburg-Landau equations. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000429354100010 |
Publication Date |
2017-10-09 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1557-1939 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
1.18 |
Times cited |
|
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 1.18 |
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Call Number |
UA @ lucian @ c:irua:150742UA @ admin @ c:irua:150742 |
Serial |
4969 |
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Permanent link to this record |
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Author |
Vanherck, J.; Bacaksiz, C.; Sorée, B.; Milošević, M.V.; Magnus, W. |
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Title |
2D ferromagnetism at finite temperatures under quantum scrutiny |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl Phys Lett |
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Volume |
117 |
Issue |
5 |
Pages |
052401 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Recent years have seen a tremendous rise of two-dimensional (2D) magnetic materials, several of which were verified experimentally. However, most of the theoretical predictions to date rely on ab initio methods, at zero temperature and fluctuation-free, while one certainly expects detrimental quantum fluctuations at finite temperatures. Here, we present the solution of the quantum Heisenberg model for honeycomb/hexagonal lattices with anisotropic exchange interaction up to third nearest neighbors and in an applied field in arbitrary direction, which answers the question whether long-range magnetization can indeed survive in the ultrathin limit of materials, up to which temperature, and what the characteristic excitation (magnon) frequencies are, all essential to envisaged applications of magnetic 2D materials. We find that long-range magnetic order persists at finite temperature for materials with overall easy-axis anisotropy. We validate the calculations on the examples of monolayers CrI3, CrBr3, and MnSe2. Moreover, we provide an easy-to-use tool to calculate Curie temperatures of new 2D computational materials. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000559330100001 |
Publication Date |
2020-08-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-6951; 1077-3118 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4 |
Times cited |
8 |
Open Access |
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|
Notes |
; This work was supported by the Research Foundation-Flanders (FWO) and the special research funds of the University of Antwerp (BOF-UA). ; |
Approved |
Most recent IF: 4; 2020 IF: 3.411 |
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Call Number |
UA @ admin @ c:irua:171176 |
Serial |
6445 |
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Permanent link to this record |
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Author |
Vanderveken, F.; Mulkers, J.; Leliaert, J.; Van Waeyenberge, B.; Sorée, B.; Zografos, O.; Ciubotaru, F.; Adelmann, C. |
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Title |
Confined magnetoelastic waves in thin waveguides |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
103 |
Issue |
5 |
Pages |
054439 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The characteristics of confined magnetoelastic waves in nanoscale ferromagnetic magnetostrictive waveguides have been investigated by a combination of analytical and numerical calculations. The presence of both magnetostriction and inverse magnetostriction leads to the coupling between confined spin waves and elastic Lamb waves. Numerical simulations of the coupled system have been used to extract the dispersion relations of the magnetoelastic waves as well as their mode profiles. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000627548800003 |
Publication Date |
2021-02-26 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
|
Open Access |
OpenAccess |
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Notes |
|
Approved |
Most recent IF: 3.836 |
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Call Number |
UA @ admin @ c:irua:177607 |
Serial |
6976 |
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Permanent link to this record |
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Author |
Vanderveken, F.; Ahmad, H.; Heyns, M.; Sorée, B.; Adelmann, C.; Ciubotaru, F. |
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Title |
Excitation and propagation of spin waves in non-uniformly magnetized waveguides |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Journal Of Physics D-Applied Physics |
Abbreviated Journal |
J Phys D Appl Phys |
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Volume |
53 |
Issue |
49 |
Pages |
495006 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The characteristics of spin waves in ferromagnetic waveguides with non-uniform magnetization have been investigated for situations where the shape anisotropy field of the waveguide is comparable to the external bias field. Spin-wave generation was realized by the magnetoelastic effect by applying normal and shear strain components, as well as by the Oersted field emitted by an inductive antenna. The magnetoelastic excitation field has a non-uniform profile over the width of the waveguide because of the non-uniform magnetization orientation, whereas the Oersted field remains uniform. Using micromagnetic simulations, we indicate that both types of excitation fields generate quantised width modes with both odd and even mode numbers as well as tilted phase fronts. We demonstrate that these effects originate from the average magnetization orientation with respect to the main axes of the magnetic waveguide. Furthermore, it is indicated that the excitation efficiency of the second-order mode generally surpasses that of the first-order mode due to their symmetry. The relative intensity of the excited modes can be controlled by the strain state as well as by tuning the dimensions of the excitation area. Finally, we demonstrate that the nonreciprocity of spin-wave radiation due to the chirality of an Oersted field generated by an inductive antenna is absent for magnetoelastic spin-wave excitation. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000575331600001 |
Publication Date |
2020-08-26 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.4 |
Times cited |
1 |
Open Access |
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|
Notes |
; This work has been supported by imec's industrial affiliate program on beyond-CMOS logic. It has also received funding from the European Union's Horizon 2020 research and innovation program within the FET-OPEN project CHIRON under grant agreement No. 801055. F V acknowledges financial support from the Research Foundation -Flanders (FWO) through grant No. 1S05719N. ; |
Approved |
Most recent IF: 3.4; 2020 IF: 2.588 |
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Call Number |
UA @ admin @ c:irua:172641 |
Serial |
6515 |
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Permanent link to this record |
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Author |
Van de Put, M.L.; Vandenberghe, W.G.; Magnus, W.; Sorée, B. |
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Title |
An envelope function formalism for lattice-matched heterostructures |
Type |
A1 Journal article |
|
Year |
2015 |
Publication |
Physica: B : condensed matter |
Abbreviated Journal |
Physica B |
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Volume |
470-471 |
Issue |
470-471 |
Pages |
69-75 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The envelope function method traditionally employs a single basis set which, in practice, relates to a single material because the k.p matrix elements are generally only known in a particular basis. In this work, we defined a basis function transformation to alleviate this restriction. The transformation is completely described by the known inter-band momentum matrix elements. The resulting envelope function equation can solve the electronic structure in lattice matched heterostructures without resorting to boundary conditions at the interface between materials, while all unit-cell averaged observables can be calculated as with the standard envelope function formalism. In the case of two coupled bands, this heterostructure formalism is equivalent to the standard formalism while taking position dependent matrix elements. (C) 2015 Elsevier B.V. All rights reserved |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000355149600011 |
Publication Date |
2015-04-26 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
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ISSN |
0921-4526; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
1.386 |
Times cited |
5 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 1.386; 2015 IF: 1.319 |
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Call Number |
c:irua:126397 |
Serial |
95 |
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Permanent link to this record |
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Author |
Osca, J.; Moors, K.; Sorée, B.; Serra, L. |
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Title |
Fabry-Perot interferometry with gate-tunable 3D topological insulator nanowires |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Nanotechnology |
Abbreviated Journal |
Nanotechnology |
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Volume |
32 |
Issue |
43 |
Pages |
435002 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Three-dimensional topological insulator (3D TI) nanowires display remarkable magnetotransport properties that can be attributed to their spin-momentum-locked surface states such as quasiballistic transport and Aharonov-Bohm oscillations. Here, we focus on the transport properties of a 3D TI nanowire with a gated section that forms an electronic Fabry-Perot (FP) interferometer that can be tuned to act as a surface-state filter or energy barrier. By tuning the carrier density and length of the gated section of the wire, the interference pattern can be controlled and the nanowire can become fully transparent for certain topological surface-state input modes while completely filtering out others. We also consider the interplay of FP interference with an external magnetic field, with which Klein tunneling can be induced, and transverse asymmetry of the gated section, e.g. due to a top-gated structure, which displays an interesting analogy with Rashba nanowires. Due to its rich conductance phenomenology, we propose a 3D TI nanowire with gated section as an ideal setup for a detailed transport-based characterization of 3D TI nanowire surface states near the Dirac point, which could be useful towards realizing 3D TI nanowire-based topological superconductivity and Majorana bound states. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000682173800001 |
Publication Date |
2021-07-20 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
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ISSN |
0957-4484 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.44 |
Times cited |
|
Open Access |
Not_Open_Access |
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Notes |
|
Approved |
Most recent IF: 3.44 |
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Call Number |
UA @ admin @ c:irua:180487 |
Serial |
6990 |
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Permanent link to this record |
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Author |
Pourghaderi, M.A.; Magnus, W.; Sorée, B.; de Meyer, K.; Meuris, M.; Heyns, M. |
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Title |
General 2D Schrödinger-Poisson solver with open boundary conditions for nano-scale CMOS transistors |
Type |
A1 Journal article |
|
Year |
2008 |
Publication |
Journal of computational electronics |
Abbreviated Journal |
J Comput Electron |
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Volume |
7 |
Issue |
4 |
Pages |
475-484 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Employing the quantum transmitting boundary (QTB) method, we have developed a two-dimensional Schrödinger-Poisson solver in order to investigate quantum transport in nano-scale CMOS transistors subjected to open boundary conditions. In this paper we briefly describe the building blocks of the solver that was originally written to model silicon devices. Next, we explain how to extend the code to semiconducting materials such as germanium, having conduction bands with energy ellipsoids that are neither parallel nor perpendicular to the channel interfaces or even to each other. The latter introduces mixed derivatives in the 2D effective mass equation, thereby heavily complicating the implementation of open boundary conditions. We present a generalized quantum transmitting boundary method that mainly leans on the completeness of the eigenstates of the effective mass equation. Finally, we propose a new algorithm to calculate the chemical potentials of the source and drain reservoirs, taking into account their mutual interaction at high drain voltages. As an illustration, we present the potential and carrier density profiles obtained for a (111) Ge NMOS transistor as well as the ballistic current characteristics. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
S.l. |
Editor |
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Language |
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Wos |
000209032500002 |
Publication Date |
2008-09-02 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1569-8025;1572-8137; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.526 |
Times cited |
3 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.526; 2008 IF: NA |
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Call Number |
UA @ lucian @ c:irua:89505 |
Serial |
1322 |
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Permanent link to this record |
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Author |
Cantoro, M.; Klekachev, A.V.; Nourbakhsh, A.; Sorée, B.; Heyns, M.M.; de Gendt, S. |
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Title |
Long-wavelength, confined optical phonons in InAs nanowires probed by Raman spectroscopy |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
European physical journal : B : condensed matter and complex systems |
Abbreviated Journal |
Eur Phys J B |
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Volume |
79 |
Issue |
4 |
Pages |
423-428 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Strongly confined nano-systems, such as one-dimensional nanowires, feature deviations in their structural, electronic and optical properties from the corresponding bulk. In this work, we investigate the behavior of long-wavelength, optical phonons in vertical arrays of InAs nanowires by Raman spectroscopy. We attribute the main changes in the spectral features to thermal anharmonicity, due to temperature effects, and rule out the contribution of quantum confinement and Fano resonances. We also observe the appearance of surface optical modes, whose details allow for a quantitative, independent estimation of the nanowire diameter. The results shed light onto the mechanisms of lineshape change in low-dimensional InAs nanostructures, and are useful to help tailoring their electronic and vibrational properties for novel functionalities. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000288120600005 |
Publication Date |
2011-02-03 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6028;1434-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.461 |
Times cited |
10 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 1.461; 2011 IF: 1.534 |
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Call Number |
UA @ lucian @ c:irua:89502 |
Serial |
1841 |
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Permanent link to this record |
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Author |
Katti, G.; Stucchi, M.; Velenis, D.; Sorée, B.; de Meyer, K.; Dehaene, W. |
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Title |
Temperature-dependent modeling and characterization of through-silicon via capacitance |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
IEEE electron device letters |
Abbreviated Journal |
Ieee Electr Device L |
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Volume |
32 |
Issue |
4 |
Pages |
563-565 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
A semianalytical model of the through-silicon via (TSV) capacitance for elevated operating temperatures is derived and verified with electrical measurements. The effect of temperature on the increase in TSV capacitance over different technology parameters is explored, and it is shown that higher oxide thickness reduces the impact of temperature rise on TSV capacitance, while with low doped substrates, which are instrumental for reducing the TSV capacitance, the sensitivity of TSV capacitance to temperature is large and cannot be ignored. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000288664800045 |
Publication Date |
2011-03-04 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
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ISSN |
0741-3106;1558-0563; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
3.048 |
Times cited |
27 |
Open Access |
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|
Notes |
; ; |
Approved |
Most recent IF: 3.048; 2011 IF: 2.849 |
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Call Number |
UA @ lucian @ c:irua:89402 |
Serial |
3498 |
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Permanent link to this record |
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Author |
Kao, K.-H.; Verhulst, A.S.; Van de Put, M.; Vandenberghe, W.G.; Sorée, B.; Magnus, W.; De Meyer, K. |
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Title |
Tensile strained Ge tunnel field-effect transistors: k\cdot p material modeling and numerical device simulation |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
115 |
Issue |
4 |
Pages |
044505-44508 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Group IV based tunnel field-effect transistors generally show lower on-current than III-V based devices because of the weaker phonon-assisted tunneling transitions in the group IV indirect bandgap materials. Direct tunneling in Ge, however, can be enhanced by strain engineering. In this work, we use a 30-band k.p method to calculate the band structure of biaxial tensile strained Ge and then extract the bandgaps and effective masses at Gamma and L symmetry points in k-space, from which the parameters for the direct and indirect band-to-band tunneling (BTBT) models are determined. While transitions from the heavy and light hole valence bands to the conduction band edge at the L point are always bridged by phonon scattering, we highlight a new finding that only the light-holelike valence band is strongly coupling to the conduction band at the Gamma point even in the presence of strain based on the 30-band k.p analysis. By utilizing a Technology Computer Aided Design simulator equipped with the calculated band-to-band tunneling BTBT models, the electrical characteristics of tensile strained Ge point and line tunneling devices are self-consistently computed considering multiple dynamic nonlocal tunnel paths. The influence of field-induced quantum confinement on the tunneling onset is included. Our simulation predicts that an on-current up to 160 (260) mu A/mu m can be achieved along with on/off ratio > 10(6) for V-DD = 0.5V by the n-type (p-type) line tunneling device made of 2.5% biaxial tensile strained Ge. (C) 2014 AIP Publishing LLC. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000331210800113 |
Publication Date |
2014-01-26 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979;1089-7550; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
26 |
Open Access |
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Notes |
; Authors would like to thank Dr. Mohammad Ali Pourghaderi for useful discussions on the nonparabolicity. Authors would also like to thank Professor Eddy Simoen and Dr. Yosuke Shimura for useful discussions about the validity of modeled bandgaps and effective masses. This work was also supported by IMEC's Industrial Affiliation Program. ; |
Approved |
Most recent IF: 2.068; 2014 IF: 2.183 |
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Call Number |
UA @ lucian @ c:irua:115800 |
Serial |
3505 |
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Permanent link to this record |
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Author |
Verhulst, A.S.; Verreck, D.; Pourghaderi, M.A.; Van de Put, M.; Sorée, B.; Groeseneken, G.; Collaert, N.; Thean, A.V.-Y. |
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Title |
Can p-channel tunnel field-effect transistors perform as good as n-channel? |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
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Volume |
105 |
Issue |
4 |
Pages |
043103 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We show that bulk semiconductor materials do not allow perfectly complementary p- and n-channel tunnel field-effect transistors (TFETs), due to the presence of a heavy-hole band. When tunneling in p-TFETs is oriented towards the gate-dielectric, field-induced quantum confinement results in a highest-energy subband which is heavy-hole like. In direct-bandgap IIIV materials, the most promising TFET materials, phonon-assisted tunneling to this subband degrades the subthreshold swing and leads to at least 10x smaller on-current than the desired ballistic on-current. This is demonstrated with quantum-mechanical predictions for p-TFETs with tunneling orthogonal to the gate, made out of InP, In0.53Ga0.47As, InAs, and a modified version of In0.53Ga0.47As with an artificially increased conduction-band density-of-states. We further show that even if the phonon-assisted current would be negligible, the build-up of a heavy-hole-based inversion layer prevents efficient ballistic tunneling, especially at low supply voltages. For p-TFET, a strongly confined n-i-p or n-p-i-p configuration is therefore recommended, as well as a tensily strained line-tunneling configuration. (C) 2014 AIP Publishing LLC. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000341152600067 |
Publication Date |
2014-07-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-6951; 1077-3118 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.411 |
Times cited |
8 |
Open Access |
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Notes |
; This work was supported by imec's industrial application program. D. Verreck acknowledges the support of a Ph.D. stipend from the Institute for Promotion of Innovation through Science and Technology in Flanders (IWT). ; |
Approved |
Most recent IF: 3.411; 2014 IF: 3.302 |
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Call Number |
UA @ lucian @ c:irua:134433 |
Serial |
4587 |
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Permanent link to this record |
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Author |
Tiwari, S.; Vanherck, J.; Van de Put, M.L.; Vandenberghe, W.G.; Sorée, B. |
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Title |
Computing Curie temperature of two-dimensional ferromagnets in the presence of exchange anisotropy |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical review research |
Abbreviated Journal |
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Volume |
3 |
Issue |
4 |
Pages |
043024 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We compare three first-principles methods of calculating the Curie temperature in two-dimensional (2D) ferromagnetic materials (FM), modeled using the Heisenberg model, and propose a simple formula for estimating the Curie temperature with high accuracy that works for all common 2D lattice types. First, we study the effect of exchange anisotropy on the Curie temperature calculated using the Monte Carlo (MC), the Green's function, and the renormalized spin-wave (RNSW) methods. We find that the Green's function method overestimates the Curie temperature in high-anisotropy regimes compared to the MC method, whereas the RNSW method underestimates the Curie temperature compared to the MC and the Green's function methods. Next, we propose a closed-form formula for calculating the Curie temperature of 2D FMs, which provides an estimate of the Curie temperature that is greatly improved over the mean-field expression for magnetic material screening. We apply the closed-form formula to predict the Curie temperature 2D magnets screened from the C2DB database and discover several high Curie temperature FMs, with Fe2F2 and MoI2 emerging as the most promising 2D ferromagnets. Finally, by comparing to experimental results for CrI3, CrCl3, and CrBr3, we conclude that for small effective anisotropies, the Green's-function-based equations are preferable, while for larger anisotropies, MC-based results are more predictive. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000707506500001 |
Publication Date |
2021-10-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182522 |
Serial |
6975 |
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Permanent link to this record |
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Author |
Tiwari, S.; Van de Put, M.; Sorée, B.; Hinkle, C.; Vandenberghe, W.G. |
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Title |
Reduction of magnetic interaction due to clustering in doped transition-metal dichalcogenides : a case study of Mn-, V-, and Fe-doped WSe₂ |
Type |
A1 Journal article |
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Year |
2024 |
Publication |
ACS applied materials and interfaces |
Abbreviated Journal |
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Volume |
16 |
Issue |
4 |
Pages |
4991-4998 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Using Hubbard-U-corrected density functional theory calculations, lattice Monte Carlo simulations, and spin Monte Carlo simulations, we investigate the impact of dopant clustering on the magnetic properties of WSe2 doped with period four transition metals. We use manganese (Mn) and iron (Fe) as candidate n-type dopants and vanadium (V) as the candidate p-type dopant, substituting the tungsten (W) atom in WSe2. Specifically, we determine the strength of the exchange interaction in Fe-, Mn-, and V-doped WSe2 in the presence of clustering. We show that the clusters of dopants are energetically more stable than discretely doped systems. Further, we show that in the presence of dopant clustering, the magnetic exchange interaction significantly reduces because the magnetic order in clustered WSe2 becomes more itinerant. Finally, we show that the clustering of the dopant atoms has a detrimental effect on the magnetic interaction, and to obtain an optimal Curie temperature, it is important to control the distribution of the dopant atoms. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
001155511900001 |
Publication Date |
2024-01-18 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1944-8244 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
9.5 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 9.5; 2024 IF: 7.504 |
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Call Number |
UA @ admin @ c:irua:203830 |
Serial |
9169 |
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Permanent link to this record |
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Author |
Verreck, D.; Verhulst, A.S.; Van de Put, M.L.; Sorée, B.; Collaert, N.; Mocuta, A.; Thean, A.; Groeseneken, G. |
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Title |
Uniform strain in heterostructure tunnel field-effect transistors |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
IEEE electron device letters |
Abbreviated Journal |
Ieee Electr Device L |
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Volume |
37 |
Issue |
37 |
Pages |
337-340 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Strain can strongly impact the performance of III-V tunnel field-effect transistors (TFETs). However, previous studies on homostructure TFETs have found an increase in ON-current to be accompanied with a degradation of subthreshold swing. We perform 30-band quantum mechanical simulations of staggered heterostructure p-n-i-n TFETs submitted to uniaxial and biaxial uniform stress and find the origin of the subthreshold degradation to be a reduction of the density of states in the strained case. We apply an alternative configuration including a lowly doped pocket in the source, which allows to take full benefit of the strain-induced increase in ON-current. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000372372100026 |
Publication Date |
2016-01-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0741-3106 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.048 |
Times cited |
17 |
Open Access |
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Notes |
; This work was supported by the imec Industrial Affiliation Program. The work of D. Verreck was supported by the Agency for Innovation by Science and Technology in Flanders. The review of this letter was arranged by Editor Z. Chen. ; |
Approved |
Most recent IF: 3.048 |
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Call Number |
UA @ lucian @ c:irua:133207 |
Serial |
4271 |
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Permanent link to this record |
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Author |
Magnus, W.; Brosens, F.; Sorée, B. |
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Title |
Modeling drive currents and leakage currents : a dynamic approach |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Journal of computational electronics |
Abbreviated Journal |
J Comput Electron |
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Volume |
8 |
Issue |
3/4 |
Pages |
307-323 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems |
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Abstract |
The dynamics of electrons and holes propagating through the nano-scaled channels of modern semiconductor devices can be seen as a widespread manifestation of non-equilibrium statistical physics and its ruling principles. In this respect both the devices that are pushing conventional CMOS technology towards the final frontiers of Moores law and the upcoming set of alternative, novel nanostructures grounded on entirely new concepts and working principles, provide an almost unlimited playground for assessing physical models and numerical techniques emerging from classical and quantum mechanical non-equilibrium theory. In this paper we revisit the Boltzmann as well as the WignerBoltzmann equation which offers a valuable platform to study transport of charge carriers taking part in drive currents. We focus on a numerical procedure that regained attention recently as an alternative tool to solve the time-dependent Boltzmann equation for inhomogeneous systems, such as the channel regions of field-effect transistors, and we discuss its extension to the WignerBoltzmann equation. Furthermore, we pay attention to the calculation of tunneling leakage currents. The latter typically occurs in nano-scaled transistors when part of the carrier distribution sustaining the drive current is found to tunnel into the gate due the presence of an ultra-thin insulating barrier separating the gate from the channel region. In particular, we discuss the paradox related to the very existence of leakage currents established by electrons occupying quasi-bound states, while the (real) wave functions of the latter cannot carry net currents. Finally, we describe a simple model to resolve the paradox as well as to estimate gate currents provided the local carrier generation rates largely exceed the tunneling rates. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
S.l. |
Editor |
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Language |
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Wos |
000208236100009 |
Publication Date |
2009-09-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1569-8025;1572-8137; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.526 |
Times cited |
4 |
Open Access |
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Notes |
|
Approved |
Most recent IF: 1.526; 2009 IF: NA |
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Call Number |
UA @ lucian @ c:irua:89503 |
Serial |
2110 |
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Permanent link to this record |