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Author |
Xu, X.; Vereecke, G.; Chen, C.; Pourtois, G.; Armini, S.; Verellen, N.; Tsai, W.K.; Kim, D.W.; Lee, E.; Lin, C.Y.; Van Dorpe, P.; Struyf, H.; Holsteyns, F.; Moshchalkov, V.; Indekeu, J.; De Gendt, S.; |
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Title |
Capturing wetting states in nanopatterned silicon |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
ACS nano |
Abbreviated Journal |
Acs Nano |
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Volume |
8 |
Issue |
1 |
Pages |
885-893 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Spectacular progress in developing advanced Si circuits with reduced size, along the track of Moore's law, has been relying on necessary developments in wet cleaning of nanopatterned Si wafers to provide contaminant free surfaces. The most efficient cleaning is achieved when complete wetting can be realized. In this work, ordered arrays of silicon nanopillars on a hitherto unexplored small scale have been used to study the wetting behavior on nanomodulated surfaces in a substantial range of surface treatments and geometrical parameters. With the use of optical reflectance measurements, the nanoscale water imbibition depths have been measured and the transition to the superhydrophobic Cassie-Baxter state has been accurately determined. For pillars of high aspect ratio (about 15), the transition occurs even when the surface is grafted with a hydrophilic functional group. We have found a striking consistent deviation between the contact angle measurements and the straightforward application of the classical wetting models. Molecular dynamics simulations show that these deviations can be attributed to the long overlooked atomic-scale surface perturbations that are introduced during the nanofabrication process. When the transition condition is approached, transient states of partial imbibition that characterize intermediate states between the Wenzel and Cassie-Baxter states are revealed in our experiments. |
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Wos |
000330542900092 |
Publication Date |
2013-12-31 |
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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 |
1936-0851;1936-086X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
13.942 |
Times cited |
39 |
Open Access |
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Notes |
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Approved |
Most recent IF: 13.942; 2014 IF: 12.881 |
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Call Number |
UA @ lucian @ c:irua:114871 |
Serial |
276 |
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Permanent link to this record |
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Author |
Clima, S.; Kaczer, B.; Govoreanu, B.; Popovici, M.; Swerts, J.; Verhulst, A.S.; Jurczak, M.; De Gendt, S.; Pourtois, G. |
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Title |
Determination of ultimate leakage through rutile TiO2 and tetragonal ZrO2 from ab initio complex band calculations |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
IEEE electron device letters |
Abbreviated Journal |
Ieee Electr Device L |
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Volume |
34 |
Issue |
3 |
Pages |
402-404 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
First-principle complex band structures have been computed for rutile TiO2 and tetragonal ZrO2 insulating materials that are of current technological relevance to dynamic random accessmemorymetal-insulator-metal (MIM) capacitors. From the magnitude of the complex wave vectors in different orientations, the most penetrating orientations have been identified. Tunneling effective masses m(tunnel) have been extracted, are shown to be a crucial parameter for the intrinsic leakage, and are identified to be an important parameter in further scaling of MIM capacitors. |
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Wos |
000315723000024 |
Publication Date |
2013-01-31 |
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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;1558-0563; |
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 |
3 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.048; 2013 IF: 3.023 |
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Call Number |
UA @ lucian @ c:irua:108295 |
Serial |
680 |
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Permanent link to this record |
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Author |
Neyts, E.C.; Thijsse, B.J.; Mees, M.J.; Bal, K.M.; Pourtois, G. |
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Title |
Establishing uniform acceptance in force biased Monte Carlo simulations |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Journal of chemical theory and computation |
Abbreviated Journal |
J Chem Theory Comput |
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Volume |
8 |
Issue |
6 |
Pages |
1865-1869 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Uniform acceptance force biased Monte Carlo (UFMC) simulations have previously been shown to be a powerful tool to simulate atomic scale processes, enabling one to follow the dynamical path during the simulation. In this contribution, we present a simple proof to demonstrate that this uniform acceptance still complies with the condition of detailed balance, on the condition that the characteristic parameter lambda = 1/2 and that the maximum allowed step size is chosen to be sufficiently small. Furthermore, the relation to Metropolis Monte Carlo (MMC) is also established, and it is shown that UFMC reduces to MMC by choosing the characteristic parameter lambda = 0 [Rao, M. et al. Mol. Phys. 1979, 37, 1773]. Finally, a simple example compares the UFMC and MMC methods. |
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Wos |
000305092400002 |
Publication Date |
2012-05-16 |
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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 |
1549-9618;1549-9626; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.245 |
Times cited |
20 |
Open Access |
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Notes |
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Approved |
Most recent IF: 5.245; 2012 IF: 5.389 |
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Call Number |
UA @ lucian @ c:irua:99090 |
Serial |
1082 |
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Permanent link to this record |
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Author |
Nishio, K.; Lu, A.K.A.; Pourtois, G. |
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Title |
Low-strain Si/O superlattices with tunable electronic properties : ab initio calculations |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
91 |
Issue |
91 |
Pages |
165303 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We propose that low-strain Si/O superlattices can be constructed by connecting reconstructed Si{001} surfaces by Si-O-Si bridges. Ab initio calculations show that our models are energetically more favorable than all the models proposed so far. The part of our Si/O superlattice model is experimentally accessible just by oxidizing a Si( 001) substrate. To complete our Si/O superlattice model, we propose a three-step method. We also explore the potential of our Si/O superlattice models for new materials used in future Si electronics. We find that the location of the channel where the carriers travel can be controlled between the interfaces and the Si layers by the insertion of O atoms into the Si-Si dimers. By revealing the origins of the interface electron and hole states, we find that similar interface states should be easily achieved for Si slabs and Si substrates. Interestingly, the interface electrons and holes have small effective masses in the direction parallel to the channel and large effective masses in the direction normal to the channel, which makes the Si/O superlattices attractive to be used for channel materials. We also find that the valley splitting of Si is enhanced by the formation of the Si/O/Si interfaces, which is ideal for developing Si-based qubits. Our findings open new perspectives to design and control the electronic properties of Si. |
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Wos |
000352986700002 |
Publication Date |
2015-04-16 |
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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 |
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 |
6 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
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Call Number |
c:irua:125998 |
Serial |
1852 |
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Permanent link to this record |
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Author |
Sorée, B.; Magnus, W.; Szepieniec, M.; Vandenbreghe, W.; Verhulst, A.; Pourtois, G.; Groeseneken, G.; de Gendt, S.; Heyns, M. |
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Title |
Novel device concepts for nanotechnology : the nanowire pinch-off FET and graphene tunnelFET |
Type |
A2 Journal article |
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Year |
2010 |
Publication |
ECS transactions |
Abbreviated Journal |
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Volume |
28 |
Issue |
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Pages |
15-26 |
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Keywords |
A2 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We explain the basic operation of a nanowire pinch-off FET and graphene nanoribbon tunnelFET. For the nanowire pinch-off FET we construct an analytical model to obtain the threshold voltage as a function of radius and doping density. We use the gradual channel approximation to calculate the current-voltage characteristics of this device and we show that the nanowire pinch-off FET has a subthreshold slope of 60 mV/dec and good ION and ION/IOFF ratios. For the graphene nanoribbon tunnelFET we show that an improved analytical model yields more realistic results for the transmission probability and hence the tunneling current. The first simulation results for the graphene nanoribbon tunnelFET show promising subthreshold slopes. |
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Wos |
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Publication Date |
0000-00-00 |
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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 |
1938-5862 |
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 |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:89510 |
Serial |
2375 |
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Permanent link to this record |
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Author |
Scarrozza, M.; Pourtois, G.; Houssa, M.; Heyns, M.; Stesmans, A. |
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Title |
Oxidation of the GaAs(001) surface : insights from first-principles calculations |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
85 |
Issue |
19 |
Pages |
195307-195307,8 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We performed a detailed investigation of the oxidation of the technologically relevant GaAs(001)-beta 2(2x4) surface via density functional calculations. The purpose is to gain insights on the atomistic mechanisms and local bondings that underlie the degradation of the surface properties once exposed to oxygen. The study comprises the adsorption of single O atoms, through the sampling of several adsorption sites, and the subsequent formation of the O adsorbate at increasing coverage by taking into account multiple-atom adsorption. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results here reported delineate a consistent picture of the initial stage of the surface oxidation: (i) at low coverage, in the limit of single O insertions, oxygen is incorporated on the surface forming a twofold-bridging Ga-O-As bond; (ii) at increasing coverage, as multiple O atoms are involved, this is accompanied by the formation of a threefold-coordinated bond (with two Ga and one As atoms); (iii) the latter has important implications regarding the electronic properties of the adsorbate since this O bonding may result in the formation of As dangling bonds. Moreover, a clear trend of increased energy gain for the incorporation of neighboring O atoms compared to single O insertions indicates that the formation of oxide clusters is favored over a regime of uniform oxidation. Our findings provide a detailed description of the O bonding and stress the importance of modeling the adsorption of multiple O atoms for an accurate description of the surface oxidation. |
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Corporate Author |
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Place of Publication |
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Language |
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Wos |
000303755700006 |
Publication Date |
2012-05-08 |
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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 |
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 |
15 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:99122 |
Serial |
2538 |
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Permanent link to this record |
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Author |
Phung, Q.M.; Vancoillie, S.; Delabie, A.; Pourtois, G.; Pierloot, K. |
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Title |
Ruthenocene and cyclopentadienyl pyrrolyl ruthenium as precursors for ruthenium atomic layer deposition : a comparative study of dissociation enthalpies |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Theoretical chemistry accounts : theory, computation, and modeling |
Abbreviated Journal |
Theor Chem Acc |
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Volume |
131 |
Issue |
7 |
Pages |
1238 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
RuCp2 (ruthenocene) and RuCpPy (cyclopentadienyl pyrrolyl ruthenium) complexes are used in ruthenium (Ru) atomic layer deposition (ALD) but exhibit a markedly different reactivity with respect to the substrate and co-reactant. In search of an explanation, we report here the results of a comparative study of the heterolytic and homolytic dissociation enthalpy of these two ruthenium complexes, making use of either density functional theory (DFT) or multiconfigurational perturbation theory (CASPT2). While both methods predict distinctly different absolute dissociation enthalpies, they agree on the relative values between both molecules. A reduced heterolytic dissociation enthalpy is obtained for RuCpPy compared to RuCp2, although the difference obtained from CASPT2 (19.9 kcal/mol) is slightly larger than the one obtained with any of the DFT functionals (around 17 kcal/mol). Both methods also agree on the more pronounced stability of the Cp- ligand in RuCpPy than in RuCp2 (by around 9 kcal/mol with DFT and by 6 kcal/mol with CASPT2). |
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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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Language |
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Wos |
000307274300003 |
Publication Date |
2012-07-07 |
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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 |
1432-881X;1432-2234; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.89 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.89; 2012 IF: 2.233 |
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Call Number |
UA @ lucian @ c:irua:101139 |
Serial |
2935 |
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Permanent link to this record |
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Author |
Scalise, E.; Houssa, M.; Pourtois, G.; Afanas'ev, V.; Stesmans, A. |
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Title |
Strain-induced semiconductor to metal transition in the two-dimensional honeycomb structure of MoS2 |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Nano Research |
Abbreviated Journal |
Nano Res |
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Volume |
5 |
Issue |
1 |
Pages |
43-48 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The electronic properties of two-dimensional honeycomb structures of molybdenum disulfide (MoS(2)) subjected to biaxial strain have been investigated using first-principles calculations based on density functional theory. On applying compressive or tensile bi-axial strain on bi-layer and mono-layer MoS(2), the electronic properties are predicted to change from semiconducting to metallic. These changes present very interesting possibilities for engineering the electronic properties of two-dimensional structures of MoS(2). |
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Corporate Author |
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Place of Publication |
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Wos |
000299085200006 |
Publication Date |
2011-11-10 |
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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 |
1998-0124;1998-0000; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
7.354 |
Times cited |
407 |
Open Access |
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Notes |
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Approved |
Most recent IF: 7.354; 2012 IF: 7.392 |
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Call Number |
UA @ lucian @ c:irua:96262 |
Serial |
3169 |
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Permanent link to this record |
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Author |
Mees, M.J.; Pourtois, G.; Neyts, E.C.; Thijsse, B.J.; Stesmans, A. |
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Title |
Uniform-acceptance force-bias Monte Carlo method with time scale to study solid-state diffusion |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
85 |
Issue |
13 |
Pages |
134301-134301,9 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Monte Carlo (MC) methods have a long-standing history as partners of molecular dynamics (MD) to simulate the evolution of materials at the atomic scale. Among these techniques, the uniform-acceptance force-bias Monte Carlo (UFMC) method [ G. Dereli Mol. Simul. 8 351 (1992)] has recently attracted attention [ M. Timonova et al. Phys. Rev. B 81 144107 (2010)] thanks to its apparent capacity of being able to simulate physical processes in a reduced number of iterations compared to classical MD methods. The origin of this efficiency remains, however, unclear. In this work we derive a UFMC method starting from basic thermodynamic principles, which leads to an intuitive and unambiguous formalism. The approach includes a statistically relevant time step per Monte Carlo iteration, showing a significant speed-up compared to MD simulations. This time-stamped force-bias Monte Carlo (tfMC) formalism is tested on both simple one-dimensional and three-dimensional systems. Both test-cases give excellent results in agreement with analytical solutions and literature reports. The inclusion of a time scale, the simplicity of the method, and the enhancement of the time step compared to classical MD methods make this method very appealing for studying the dynamics of many-particle systems. |
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Place of Publication |
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Language |
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Wos |
000302290500001 |
Publication Date |
2012-04-03 |
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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 |
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 |
31 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:97160 |
Serial |
3809 |
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Permanent link to this record |
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Author |
Scalise, E.; Houssa, M.; Pourtois, G.; van den Broek, B.; Afanas'ev, V.; Stesmans, A. |
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Title |
Vibrational properties of silicene and germanene |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Nano Research |
Abbreviated Journal |
Nano Res |
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Volume |
6 |
Issue |
1 |
Pages |
19-28 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The structural and vibrational properties of two-dimensional hexagonal silicon (silicene) and germanium (germanene) are investigated by means of first-principles calculations. It is predict that the silicene (germanene) structure with a small buckling of 0.44 (0.7 ) and bond lengths of 2.28 (2.44 ) is energetically the most favorable, and it does not exhibit imaginary phonon mode. The calculated non-resonance Raman spectra of silicene is characterized by a main peak at about 575 cm(-1), namely the G-like peak. For germanene, the highest peak is at about 290 cm(-1). Extensive calculations on armchair silicene nanoribbons and armchair germanene nanoribbons are also performed, with and without hydrogenation of the edges. The studies reveal other Raman peaks mainly distributed at lower frequencies than the G-like peak which could be attributed to the defects at the edges of the ribbons, thus not present in the Raman spectra of non-defective silicene and germanene. Particularly the Raman peak corresponding to the D mode is found to be located at around 515 cm(-1) for silicene and 270 cm(-1) for germanene. The calculated G-like and the D peaks are likely the fingerprints of the Raman spectra of the low-buckled structures of silicene and germanene. |
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Corporate Author |
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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 |
000313658800003 |
Publication Date |
2012-12-17 |
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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 |
1998-0124;1998-0000; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
7.354 |
Times cited |
105 |
Open Access |
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Notes |
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Approved |
Most recent IF: 7.354; 2013 IF: 6.963 |
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Call Number |
UA @ lucian @ c:irua:110106 |
Serial |
3846 |
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Permanent link to this record |
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Author |
Clima, S.; Chen, Y.Y.; Fantini, A.; Goux, L.; Degraeve, R.; Govoreanu, B.; Pourtois, G.; Jurczak, M. |
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Title |
Intrinsic tailing of resistive states distributions in amorphous <tex>HfOx </tex> and TaOx based resistive random access memories |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
IEEE electron device letters |
Abbreviated Journal |
Ieee Electr Device L |
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Volume |
36 |
Issue |
36 |
Pages |
769-771 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We report on the ineffectiveness of programming oxide-based resistive random access memory (OxRAM) at low current with a program and verify algorithm due to intrinsic relaxation of the verified distribution to the natural state distribution obtained by single-pulse programming without verify process. Based on oxygen defect formation thermodynamics and on their diffusion barriers in amorphous HfOx and TaOx, we describe the intrinsic nature of tailing of the verified low resistive state and high resistive state distributions. We introduce different scenarios to explain fast distribution widening phenomenon, which is a fundamental limitation for OxRAM current scaling and device reliability. |
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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 |
|
Wos |
000358570300011 |
Publication Date |
2015-06-23 |
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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 |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
0741-3106 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.048 |
Times cited |
33 |
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 3.048; 2015 IF: 2.754 |
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Call Number |
UA @ lucian @ c:irua:134412 |
Serial |
4200 |
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Permanent link to this record |
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Author |
Sankaran, K.; Swerts, J.; Couet, S.; Stokbro, K.; Pourtois, G. |
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Title |
Oscillatory behavior of the tunnel magnetoresistance due to thickness variations in Ta vertical bar CoFe vertical bar MgO magnetic tunnel junctions : a first-principles study |
Type |
A1 Journal article |
|
Year |
2016 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
94 |
Issue |
94 |
Pages |
094424 |
|
|
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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|
Abstract |
To investigate the impact of both the CoFe ferromagnetic layer thickness and the capping paramagnetic layer on the tunnel magnetoresistance (TMR), we performed first-principles simulations on epitaxial magnetic tunnel junctions contacted with either CoFe or Ta paramagnetic capping layers. We observed a strong oscillation of the TMR amplitude with respect to the thickness of the ferromagnetic layer. The TMR is found to be amplified whenever the MgO spin tunnel barrier is thickened. Quantization of the electronic structure of the ferromagnetic layers is found to be at the origin of this oscillatory behavior. Metals such as Ta contacting the magnetic layer are found to enhance the amplitude of the oscillations due to the occurrence of an interface dipole. The latter drives the band alignment and tunes the nature of the spin channels that are active during the tunneling process. Subsequently, the regular transmission spin channels are modulated in the magnetic tunnel junction stack and other complex ones are being activated. |
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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 |
000383860700004 |
Publication Date |
2016-09-20 |
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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 |
|
Series Issue |
|
Edition |
|
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|
ISSN |
2469-9950;2469-9969; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
3.836 |
Times cited |
4 |
Open Access |
|
|
|
Notes |
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Approved |
Most recent IF: 3.836 |
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|
Call Number |
UA @ lucian @ c:irua:137122 |
Serial |
4468 |
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Permanent link to this record |
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Author |
van den Broek, B.; Houssa, M.; Lu, A.; Pourtois, G.; Afanas'ev, V.; Stesmans, A. |
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Title |
Silicene nanoribbons on transition metal dichalcogenide substrates : effects on electronic structure and ballistic transport |
Type |
A1 Journal article |
|
Year |
2016 |
Publication |
Nano Research |
Abbreviated Journal |
Nano Res |
|
|
Volume |
9 |
Issue |
9 |
Pages |
3394-3406 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The idea of stacking multiple monolayers of different two-dimensional materials has become a global pursuit. In this work, a silicene armchair nanoribbon of width W and van der Waals-bonded to different transition-metal dichalcogenide (TMD) bilayer substrates MoX2 and WX2, where X = S, Se, Te is considered. The orbital resolved electronic structure and ballistic transport properties of these systems are simulated by employing van der Waals-corrected density functional theory and nonequilibrium Green's functions. We find that the lattice mismatch with the underlying substrate determines the electronic structure, correlated with the silicene buckling distortion and ultimately with the contact resistance of the two-terminal system. The smallest lattice mismatch, obtained with the MoTe2 substrate, results in the silicene ribbon properties coming close to those of a freestanding one. With the TMD bilayer acting as a dielectric layer, the electronic structure is tunable from a direct to an indirect semiconducting layer, and subsequently to a metallic electronic dispersion layer, with a moderate applied perpendicular electric field. |
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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 |
|
Wos |
000386770300018 |
Publication Date |
2016-08-20 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1998-0124 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
7.354 |
Times cited |
2 |
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 7.354 |
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Call Number |
UA @ lucian @ c:irua:138210 |
Serial |
4469 |
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Permanent link to this record |
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Author |
de de Meux, A.J.; Bhoolokam, A.; Pourtois, G.; Genoe, J.; Heremans, P. |
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Title |
Oxygen vacancies effects in a-IGZO : formation mechanisms, hysteresis, and negative bias stress effects |
Type |
A1 Journal article |
|
Year |
2017 |
Publication |
Physica status solidi : A : applications and materials science |
Abbreviated Journal |
Phys Status Solidi A |
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Volume |
214 |
Issue |
6 |
Pages |
1600889 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The amorphous oxide semiconductor Indium-Gallium-Zinc-Oxide (a-IGZO) has gained a large technological relevance as a semiconductor for thin-film transistors in active-matrix displays. Yet, major questions remain unanswered regarding the atomic origin of threshold voltage control, doping level, hysteresis, negative bias stress (NBS), and negative bias illumination stress (NBIS). We undertake a systematic study of the effects of oxygen vacancies on the properties of a-IGZO by relating experimental observations to microscopic insights gained from first-principle simulations. It is found that the amorphous nature of the semiconductor allows unusually large atomic relaxations. In some cases, oxygen vacancies are found to behave as perfect shallow donors without the formation of structural defects. Once structural defects are formed, their transition states can vary upon charge and discharge cycles. We associate this phenomenon to a possible presence of hysteresis in the transfer curve of the devices. Under NBS, the creation of oxygen vacancies becomes energetically very stable, hence thermodynamically very likely. This generation process is correlated with the occurrence of the negative bias stress instabilities observed in a-IGZO transistors. While oxygen vacancies can therefore be related to NBS and hysteresis, it appears unlikely from our results that they are direct causes of NBIS, contrary to common belief. |
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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 |
000403339900012 |
Publication Date |
2017-03-02 |
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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 |
|
Series Issue |
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Edition |
|
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ISSN |
1862-6300 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
1.775 |
Times cited |
8 |
Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 1.775 |
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Call Number |
UA @ lucian @ c:irua:144219 |
Serial |
4678 |
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Permanent link to this record |
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Author |
Lu, A.K.A.; Houssa, M.; Radu, I.P.; Pourtois, G. |
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Title |
Toward an understanding of the electric field-induced electrostatic doping in van der Waals heterostructures : a first-principles study |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
ACS applied materials and interfaces |
Abbreviated Journal |
Acs Appl Mater Inter |
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Volume |
9 |
Issue |
8 |
Pages |
7725-7734 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Since the discovery of graphene, a broad range of two-dimensional (2D) materials has captured the attention of the scientific communities. Materials, such as hexagonal boron nitride (hBN) and the transition metal dichalcogenides (TMDs) family, have shown promising semiconducting and insulating properties that are very appealing for the semiconductor industry. Recently, the possibility of taking advantage of the properties of 2D-based heterostructures has been investigated for low-power nanoelectronic applications. In this work, we aim at evaluating the relation between the nature of the materials used in such heterostructures and the amplitude of the layer-to-layer charge transfer induced by an external electric field, as is typically present in nanoelectronic gated devices. A broad range of combinations of TMDs, graphene, and hBN has been investigated using density functional theory. Our results show that the electric field induced charge transfer strongly depends on the nature of the 2D materials used in the van der Waals heterostructures and to a lesser extent on the relative orientation of the materials in the structure. Our findings contribute to the building of the fundamental understanding required to engineer electrostatically the doping of 2D materials and to establish the factors that drive the charge transfer mechanisms in electron tunneling-based devices. These are key ingredients for the development of 2D -based nanoelectronic devices. |
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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 |
000395494200119 |
Publication Date |
2017-02-13 |
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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 |
1944-8244 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
7.504 |
Times cited |
10 |
Open Access |
Not_Open_Access |
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Notes |
|
Approved |
Most recent IF: 7.504 |
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Call Number |
UA @ lucian @ c:irua:142483 |
Serial |
4696 |
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Permanent link to this record |
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Author |
Dabral, A.; Lu, A.K.A.; Chiappe, D.; Houssa, M.; Pourtois, G. |
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Title |
A systematic study of various 2D materials in the light of defect formation and oxidation |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Physical chemistry, chemical physics |
Abbreviated Journal |
Phys Chem Chem Phys |
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Volume |
21 |
Issue |
3 |
Pages |
1089-1099 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The thermodynamic aspects of various 2D materials are explored using Density Functional Theory (DFT). Various metal chalcogenides (MX2, M = metal, chalcogen X = S, Se, Te) are investigated with respect to their interaction and stability under different ambient conditions met in the integration process of a transistor device. Their interaction with high- dielectrics is also addressed, in order to assess their possible integration in Complementary Metal Oxide Semiconductor (CMOS) field effect transistors. 2D materials show promise for high performance nanoelectronic devices, but the presence of defects (vacancies, grain boundaries,...) can significantly impact their electronic properties. To assess the impact of defects, their enthalpies of formation and their signature levels in the density of states have been studied. We find, consistently with literature reports, that chalcogen vacancies are the most likely source of defects. It is shown that while pristine 2D materials are in general stable whenever set in contact with different ambient atmospheres, the presence of defective sites affects the electronic properties of the 2D materials to varying degrees. We observe that all the 2D materials studied in the present work show strong reactivity towards radical oxygen plasma treatments while reactivity towards other common gas phase chemical such as O-2 and H2O and groups present at the high- surface varies significantly between species. While energy band-gaps, effective masses and contact resistivities are key criteria in selection of 2D materials for scaled CMOS and tunneling based devices, the phase and ambient stabilities might also play a very important role in the development of reliable nanoelectronic applications. |
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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 |
000456147000009 |
Publication Date |
2018-12-19 |
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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 |
1463-9076; 1463-9084 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.123 |
Times cited |
1 |
Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 4.123 |
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Call Number |
UA @ admin @ c:irua:156715 |
Serial |
5267 |
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Permanent link to this record |
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Author |
Vohra, A.; Khanam, A.; Slotte, J.; Makkonen, I.; Pourtois, G.; Loo, R.; Vandervorst, W. |
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Title |
Evolution of phosphorus-vacancy clusters in epitaxial germanium |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
125 |
Issue |
2 |
Pages |
025701 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The E centers (dopant-vacancy pairs) play a significant role in dopant deactivation in semiconductors. In order to gain insight into dopant-defect interactions during epitaxial growth of in situ phosphorus doped Ge, positron annihilation spectroscopy, which is sensitive to open-volume defects, was performed on Ge layers grown by chemical vapor deposition with different concentrations of phosphorus (similar to 1 x 10(18)-1 x 10(20) cm(-3)). Experimental results supported by first-principles calculations based on the two component density-functional theory gave evidence for the existence of mono-vacancies decorated by several phosphorus atoms as the dominant defect type in the epitaxial Ge. The concentration of vacancies increases with the amount of P-doping. The number of P atoms around the vacancy also increases, depending on the P concentration. The evolution of P-n-V clusters in Ge contributes significantly to the dopant deactivation. Published under license by AIP Publishing. |
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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 |
000455922100057 |
Publication Date |
2019-01-08 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
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 |
|
|
Impact Factor |
2.068 |
Times cited |
5 |
Open Access |
Not_Open_Access |
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Notes |
|
Approved |
Most recent IF: 2.068 |
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Call Number |
UA @ admin @ c:irua:156722 |
Serial |
5274 |
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Permanent link to this record |
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Author |
Dhayalan, S.K.; Nuytten, T.; Pourtois, G.; Simoen, E.; Pezzoli, F.; Cinquanta, E.; Bonera, E.; Loo, R.; Rosseel, E.; Hikavyy, A.; Shimura, Y.; Vandervorst, W. |
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Title |
Insights into the C Distribution in Si:C/Si:C:P and the Annealing Behavior of Si:C Layers |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
ECS journal of solid state science and technology |
Abbreviated Journal |
Ecs J Solid State Sc |
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Volume |
8 |
Issue |
4 |
Pages |
P209-P216 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Si:C and Si:C:P alloys are potential candidates for source-drain stressor applications in n-type Fin Field Effect Transistors (FinFETs). Increasing the C content to achieve high strain results in the arrangement of C atoms as third nearest neighbors (3nn) in the Si: C lattice. During thermal annealing, the presence of C atoms as 3nn may promote clustering at the interstitial sites, causing loss of stress. The concentration of C atoms as 3nn is reduced by the incorporation of a small amount of Ge atoms during the growth, whereas in-situ P doping does not influence this 3nn distribution [J Solid State Sci. Technol vol 6, p 755, 2017]. Small amounts of Ge are provided during low temperature selective epitaxial growth scheme, which are based on cyclic deposition and etching (CDE). In this work, we aim to provide physical insights into the aforementioned phenomena, to understand the behavior of 3nn C atoms and the types of defects that are formed in the annealed Si: C films. Using ab-initio simulations, the Ge-C interaction in the Si matrix is investigated and this insight is used to explain how the Ge incorporation leads to a reduced 3nn distribution of the C atoms. The interaction between C and P in the Si: C: P films is also investigated to explain why the P incorporation has not led to a reduction in the 3nn distribution. We then report on the Raman characterization of Si: C layers subjected to post epi annealing. As the penetration depth of the laser is dependent on the wavelength, Raman measurements at two different wavelengths enable us to probe the depth distribution of 3nn C atoms after applying different annealing conditions. We observed a homogeneous loss in 3nn C throughout the layer. Whereas in the kinematic modeling of high resolution X-ray diffraction spectra, a gradient in the substitutional C loss was observed close to the epitaxial layer/substrate interface. This gradient can be due to the out diffusion of C atoms into the Si substrate or to the formation of interstitial C clusters, which cannot be distinguished in HR-XRD. Deep Level Transient Spectroscopy indicated that the prominent out-diffusing species was interstitial CO complex while the interstitial C defects were also prevalent in the epi layer. (c) 2019 The Electrochemical Society. |
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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 |
000465069200001 |
Publication Date |
2019-04-18 |
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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 |
2162-8769; 2162-8777 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
1.787 |
Times cited |
|
Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 1.787 |
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Call Number |
UA @ admin @ c:irua:160399 |
Serial |
5275 |
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Permanent link to this record |
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Author |
Vohra, A.; Khanam, A.; Slotte, J.; Makkonen, I.; Pourtois, G.; Porret, C.; Loo, R.; Vandervorst, W. |
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Title |
Heavily phosphorus doped germanium : strong interaction of phosphorus with vacancies and impact of tin alloying on doping activation |
Type |
A1 Journal article |
|
Year |
2019 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
|
|
Volume |
125 |
Issue |
22 |
Pages |
225703 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We examined the vacancy trapping proficiency of Sn and P atoms in germanium using positron annihilation spectroscopy measurements, sensitive to the open-volume defects. Epitaxial Ge1 xSnx films were grown by chemical vapor deposition with different P concentrations in the 3: 0 1019-1: 5 1020 cm 3 range. We corroborate our findings with first principles simulations. Codoping of Ge with a Sn concentration of up to 9% is not an efficient method to suppress the free vacancy concentration and the formation of larger phosphorus-vacancy complexes. Experimental results confirm an increase in the number of P atoms around the monovacancy with P-doping, leading to dopant deactivation in epitaxial germanium-tin layers with similar Sn content. Vice versa, no impact on the improvement of maximum achieved P activation in Ge with increasing Sn-doping has been observed. Theoretical calculations also confirm that Pn-V (vacancy) complexes are energetically more stable than the corresponding SnmPn-V and Snm-V defect structures with the same number of alien atoms (Sn or P) around the monovacancy. he strong attraction of vacancies to the phosphorus atoms remains the dominant dopant deactivation mechanism in Ge as well as in Ge1 xSnx. Published under license by AIP Publishing. |
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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 |
000471698600044 |
Publication Date |
2019-06-10 |
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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 |
0021-8979; 1089-7550 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
2.068 |
Times cited |
1 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.068 |
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Call Number |
UA @ admin @ c:irua:161333 |
Serial |
6300 |
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Permanent link to this record |
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Author |
Clima, S.; Garbin, D.; Devulder, W.; Keukelier, J.; Opsomer, K.; Goux, L.; Kar, G.S.; Pourtois, G. |
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Title |
Material relaxation in chalcogenide OTS SELECTOR materials |
Type |
A1 Journal article |
|
Year |
2019 |
Publication |
Microelectronic engineering |
Abbreviated Journal |
Microelectron Eng |
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Volume |
215 |
Issue |
215 |
Pages |
110996 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Nature of the mobility-gap states in amorphous Ge-rich Ge50Se50 was found to be related to homopolar Ge bonds in the chains/clusters of Ge atoms. Threshold switching material suffers Ge-Ge bond concentration drift during material ageing, which can explain the observed reliability of the aGe(50)Se(50) selector devices. Strong Ge-N bonds were introduced to alleviate the observed instability. |
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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 |
000480665600008 |
Publication Date |
2019-05-21 |
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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 |
0167-9317 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
1.806 |
Times cited |
1 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.806 |
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Call Number |
UA @ admin @ c:irua:161905 |
Serial |
6308 |
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Permanent link to this record |
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Author |
Khanam, A.; Vohra, A.; Slotte, J.; Makkonen, I.; Loo, R.; Pourtois, G.; Vandervorst, W. |
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Title |
A demonstration of donor passivation through direct formation of V-As-i complexes in As-doped Ge1-XSnx |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Journal Of Applied Physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
127 |
Issue |
19 |
Pages |
195703 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Positron annihilation spectroscopy in the Doppler and coincidence Doppler mode was applied on Ge1 xSnx epitaxial layers, grown by chemical vapor deposition with different total As concentrations (1019-1021 cm3), high active As concentrations (1019 cm3), and similar Sn concentrations (5.9%-6.4%). Positron traps are identified as mono-vacancy complexes. Vacancy-As complexes, V-Asi, formed during the growth were studied to deepen the understanding of the electrical passivation of the Ge1 xSnx:As epilayers. Larger monovacancy complexes, V-Asi (i 2), are formed as the As doping increases. The total As concentration shows a significant impact on the saturation of the number of As atoms (i 1/4 4) around the vacancies in the sample epilayers. The presence of V-Asi complexes decreases the dopant activation in the Ge1 xSnx:As epilayers. Furthermore, the presence of Sn failed to hinder the formation of larger V-Asi complexes and thus failed to reduce the donor-deactivation. |
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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 |
000536196000003 |
Publication Date |
2020-05-15 |
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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 |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.2 |
Times cited |
|
Open Access |
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|
Notes |
; ; |
Approved |
Most recent IF: 3.2; 2020 IF: 2.068 |
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Call Number |
UA @ admin @ c:irua:170252 |
Serial |
6447 |
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Permanent link to this record |
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Author |
Mehta, A.N.; Mo, J.; Pourtois, G.; Dabral, A.; Groven, B.; Bender, H.; Favia, P.; Caymax, M.; Vandervorst, W. |
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Title |
Grain-boundary-induced strain and distortion in epitaxial bilayer MoS₂ lattice |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
|
|
Volume |
124 |
Issue |
11 |
Pages |
6472-6478 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Grain boundaries between 60 degrees rotated and twinned crystals constitute the dominant type of extended line defects in two-dimensional transition metal dichalcogenides (2D MX2) when grown on a single crystalline template through van der Waals epitaxy. The two most common 60 degrees grain boundaries in MX2 layers, i.e., beta- and gamma-boundaries, introduce distinct distortion and strain into the 2D lattice. They impart a localized tensile or compressive strain on the subsequent layer, respectively, due to van der Waals coupling in bilayer MX2 as determined by combining atomic resolution electron microscopy, geometric phase analysis, and density functional theory. Based on these observations, an alternate route to strain engineering through controlling intrinsic van der Waals forces in homobilayer MX2 is proposed. In contrast to the commonly used external means, this approach enables the localized application of strain to tune the electronic properties of the 2D semiconducting channel in ultra-scaled nanoelectronic applications. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000526396000067 |
Publication Date |
2020-02-21 |
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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 |
3.7 |
Times cited |
2 |
Open Access |
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|
Notes |
; ; |
Approved |
Most recent IF: 3.7; 2020 IF: 4.536 |
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Call Number |
UA @ admin @ c:irua:168625 |
Serial |
6528 |
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Permanent link to this record |
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Author |
Clima, S.; Garbin, D.; Opsomer, K.; Avasarala, N.S.; Devulder, W.; Shlyakhov, I.; Keukelier, J.; Donadio, G.L.; Witters, T.; Kundu, S.; Govoreanu, B.; Goux, L.; Detavernier, C.; Afanas'ev, V.; Kar, G.S.; Pourtois, G. |
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Title |
Ovonic threshold-switching GexSey chalcogenide materials : stoichiometry, trap nature, and material relaxation from first principles |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Physica Status Solidi-Rapid Research Letters |
Abbreviated Journal |
Phys Status Solidi-R |
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Volume |
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Issue |
|
Pages |
1900672 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
Density functional theory simulations are used to identify the structural factors that define the material properties of ovonic threshold switches (OTS). They show that the nature of mobility-gap trap states in amorphous Ge-rich Ge50Se50 is related to Ge-Ge bonds, whereas in Se-rich Ge30Se70 the Ge valence-alternating-pairs and Se lone-pairs dominate. To obtain a faithful description of the electronic structure and delocalization of states, it is required to combine hybrid exchange-correlation functionals with large unit-cell models. The extent of localization of electronic states depends on the applied external electric field. Hence, OTS materials undergo structural changes during electrical cycling of the device, with a decrease in the population of less exothermic Ge-Ge bonds in favor of more exothermic Ge-Se. This reduces the amount of charge traps, which translates into coordination changes, an increase in mobility-gap, and subsequently changes in the selector-device electrical parameters. The threshold voltage drift process can be explained by natural evolution of the nonpreferred Ge-Ge bonds (or “chains”/clusters thereof) in Ge-rich GexSe1-x. The effect of extrinsic doping is shown for Si and N, which introduce strong covalent bonds into the system, increase both mobility-gap and crystallization temperature, and decrease the leakage current. |
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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 |
000512431100001 |
Publication Date |
2020-01-28 |
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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 |
|
Series Issue |
|
Edition |
|
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|
ISSN |
1862-6254 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.8 |
Times cited |
3 |
Open Access |
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Notes |
; This work was carried out in the framework of the imec Core CMOS-Emerging Memory Program. Financial support from EU H2020-NMBPTO-IND-2018 project “INTERSECT” (Grant No. 814487) is acknowledged. ; |
Approved |
Most recent IF: 2.8; 2020 IF: 3.032 |
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Call Number |
UA @ admin @ c:irua:166492 |
Serial |
6575 |
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Permanent link to this record |
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Author |
Vohra, A.; Makkonen, I.; Pourtois, G.; Slotte, J.; Porret, C.; Rosseel, E.; Khanam, A.; Tirrito, M.; Douhard, B.; Loo, R.; Vandervorst, W. |
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Title |
Source/drain materials for Ge nMOS devices: phosphorus activation in epitaxial Si, Ge, Ge1-xSnx and SiyGe1-x-ySnx |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Ecs Journal Of Solid State Science And Technology |
Abbreviated Journal |
Ecs J Solid State Sc |
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Volume |
9 |
Issue |
4 |
Pages |
044010-44012 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
This paper benchmarks various epitaxial growth schemes based on n-type group-IV materials as viable source/drain candidates for Ge nMOS devices. Si:P grown at low temperature on Ge, gives an active carrier concentration as high as 3.5 x 10(20) cm(-3) and a contact resistivity down to 7.5 x 10(-9) Omega.cm(2). However, Si:P growth is highly defective due to large lattice mismatch between Si and Ge. Within the material stacks assessed, one option for Ge nMOS source/drain stressors would be to stack Si:P, deposited at contact level, on top of a selectively grown n-SiyGe1-x-ySnx at source/drain level, in line with the concept of Si passivation of n-Ge surfaces to achieve low contact resistivities as reported in literature (Martens et al. 2011 Appl. Phys. Lett., 98, 013 504). The saturation in active carrier concentration with increasing P (or As)-doping is the major bottleneck in achieving low contact resistivities for as-grown Ge or SiyGe1-x-ySnx. We focus on understanding various dopant deactivation mechanisms in P-doped Ge and Ge1-xSnx alloys. First principles simulation results suggest that P deactivation in Ge and Ge1-xSnx can be explained both by P-clustering and donor-vacancy complexes. Positron annihilation spectroscopy analysis, suggests that dopant deactivation in P-doped Ge and Ge1-xSnx is primarily due to the formation of P-n-V and SnmPn-V clusters. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000531473500002 |
Publication Date |
2020-04-27 |
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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 |
2162-8769; 2162-8777 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.2 |
Times cited |
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Open Access |
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Notes |
; The imec core CMOS program members, European Commission, the TAKEMI5 ECSEL project, local authorities and the imec pilot line are acknowledged for their support. Air Liquide Advanced Materials is acknowledged for providing advanced precursor gases. A. V. acknowledges his long stay abroad grant and a grant for participation in congress abroad from the Research Foundation-Flanders (Application No. V410518N and K159219N). I. M. acknowledges financial support from Academy of Finland (Project Nos. 285 809, 293 932 and 319 178). CSC-IT Center for Science, Finland is acknowledged for providing the computational resources. ; |
Approved |
Most recent IF: 2.2; 2020 IF: 1.787 |
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Call Number |
UA @ admin @ c:irua:169502 |
Serial |
6607 |
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Permanent link to this record |
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Author |
Guo, J.; Clima, S.; Pourtois, G.; Van Houdt, J. |
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Title |
Identifying alternative ferroelectric materials beyond Hf(Zr)O-₂ |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl Phys Lett |
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Volume |
117 |
Issue |
26 |
Pages |
262903 |
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Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
A database-driven approach combined with ab initio density functional theory (DFT) simulations is used to identify and simulate alternative ferroelectric materials beyond Hf(Zr)O-2. The database-driven screening method identifies a class of wurtzite ferroelectric materials. DFT simulations of wurtzite magnesium chalcogenides, including MgS, MgSe, and MgTe, show their potential to achieve improved ferroelectric (FE) stability, simple atomistic unit cell structure, and large FE polarization. Strain engineering can effectively modulate the FE switching barrier height for facilitating FE switching. The effect of the piezoelectric property on the FE switching barrier heights is also examined. |
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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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Wos |
000608049700003 |
Publication Date |
2020-12-28 |
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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 |
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 |
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Open Access |
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Notes |
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Approved |
Most recent IF: 4; 2020 IF: 3.411 |
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Call Number |
UA @ admin @ c:irua:176053 |
Serial |
6766 |
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Permanent link to this record |
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Author |
Adelmann, C.; Sankaran, K.; Dutta, S.; Gupta, A.; Kundu, S.; Jamieson, G.; Moors, K.; Pinna, N.; Ciofi, I.; Van Elshocht, S.; Bommels, J.; Boccardi, G.; Wilson, C.J.; Pourtois, G.; Tokei, Z. |
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Title |
Alternative Metals: from ab initio Screening to Calibrated Narrow Line Models |
Type |
P1 Proceeding |
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Year |
2018 |
Publication |
Proceedings of the IEEE ... International Interconnect Technology Conference
T2 – IEEE International Interconnect Technology Conference (IITC), JUN 04-07, 2018, Santa Clara, CA |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
154-156 |
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Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We discuss the selection and assessment of alternative metals by a combination of ab initio computation of electronic properties, experimental resistivity assessments, and calibrated line resistance models. Pt-group metals as well as Nb are identified as the most promising elements, with Ru showing the best combination of material properties and process maturity. An experimental assessment of the resistivity of Ru, Ir, and Co lines down to similar to 30 nm(2) is then used to devise compact models for line and via resistance that can be compared to Cu predictions. The main advantage of alternative metals originates from the possibility for barrierless metallization. |
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Place of Publication |
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Wos |
000468672900051 |
Publication Date |
2018-09-06 |
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Series Editor |
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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 |
978-1-5386-4337-2; 978-1-5386-4337-2 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
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:160473 |
Serial |
7436 |
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Permanent link to this record |
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Author |
Sankaran, K.; Swerts, J.; Carpenter, R.; Couet, S.; Garello, K.; Evans, R.F.L.; Rao, S.; Kim, W.; Kundu, S.; Crotti, D.; Kar, G.S.; Pourtois, G. |
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Title |
Evidence of magnetostrictive effects on STT-MRAM performance by atomistic and spin modeling |
Type |
P1 Proceeding |
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Year |
2018 |
Publication |
2018 Ieee International Electron Devices Meeting (iedm) |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
For the first time, we demonstrate, using an atomistic description of a 30nm diameter spin-transfer-torque magnetic random access memories (STT-MRAM), that the difference in mechanical properties of its sub-nanometer layers induces a high compressive strain in the magnetic tunnel junction (MTJ) and leads to a detrimental magnetostrictive effect. Our model explains the issues met in engineering the electrical and magnetic performances in scaled STT-MRAM devices. The resulting high compressive strain built in the stack, particularly in the MgO tunnel barrier (t-MgO), and its associated non-uniform atomic displacements, impacts on the quality of the MTJ interface and leads to strain relieve mechanisms such as surface roughness and adhesion issues. We illustrate that the strain gradient induced by the different materials and their thicknesses in the stacks has a negative impact on the tunnel magneto-resistance (TMR), on the magnetic nucleation process and on the STT-MRAM performance. |
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Wos |
000459882300147 |
Publication Date |
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Series Editor |
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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 |
978-1-72811-987-8; 978-1-72811-987-8 |
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:158694 |
Serial |
7942 |
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Permanent link to this record |
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Author |
Clima, S.; O'Sullivan, B.J.; Ronchi, N.; Bardon, M.G.; Banerjee, K.; Van den Bosch, G.; Pourtois, G.; van Houdt, J. |
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Title |
Ferroelectric switching in FEFET : physics of the atomic mechanism and switching dynamics in HfZrOx, HfO2 with oxygen vacancies and Si dopants |
Type |
P1 Proceeding |
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Year |
2020 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
P1 Proceeding; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The fine balance between dipole-field energy and anion drift force defines the switching mechanism during polarization reversal: for the first time we show that only Pbcm mechanism obeys the ferroelectric switching physics, whereas P4(2)/nmc (or any other) mechanism does not. However, with lower energy barrier, it represents an important antiferroelectric mechanism. Constraints relaxation can lead to 90 degrees polarization rotation (domain deactivation). Intrinsically, the Si/VO-doping can switch faster than undoped HfO2 or HfZrOx. Theoretical Arrhenius model / intrinsic material switching (DFT) overestimates the switching speed extracted from experiments. |
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Place of Publication |
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Wos |
000717011600218 |
Publication Date |
2021-03-11 |
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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 |
978-1-7281-8888-1 |
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 |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:184730 |
Serial |
7963 |
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Permanent link to this record |
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Author |
Clima, S.; McMitchell, S.R.C.; Florent, K.; Nyns, L.; Popovici, M.; Ronchi, N.; Di Piazza, L.; Van Houdt, J.; Pourtois, G. |
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Title |
First-principles perspective on poling mechanisms and ferroelectric/antiferroelectric behavior of Hf1-xZrxO2 for FEFET applications |
Type |
P1 Proceeding |
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Year |
2018 |
Publication |
2018 Ieee International Electron Devices Meeting (iedm) |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
We investigate at the atomic level the most probable phase transformations under strain, that are responsible for the ferroelectric/ antiferroelectric behavior in Hf1-xZrxO2 materials. Four different crystalline phase transformations exhibit a polar/non-polar transition: monoclinic-to-orthorhombic requires a gliding strain tensor, orthorhombic-to-orthorhombic transformation does not need strain to polarize the material, whereas tetragonal-to-cubic cell compression and tetragonal-to-orthorhombic cell elongation destabilizes the non-polar tetragonal phase, facilitating the transition towards a polar atomic configuration, therefore changing the polarization-electric field loop from antiferroelectric to ferroelectric. Oxygen vacancies can reduce drastically the polarization reversal barriers. |
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Place of Publication |
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Language |
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Wos |
000459882300073 |
Publication Date |
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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 |
978-1-72811-987-8; 978-1-72811-987-8 |
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:158693 |
Serial |
7972 |
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Permanent link to this record |
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Author |
Sankaran, K.; Moors, K.; Dutta, S.; Adelmann, C.; Tokei, Z.; Pourtois, G. |
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Title |
Metallic ceramics for low resitivity interconnects : an ab initio insight |
Type |
P1 Proceeding |
|
Year |
2018 |
Publication |
Proceedings of the IEEE ... International Interconnect Technology Conference
T2 – IEEE International Interconnect Technology Conference (IITC), JUN 04-07, 2018, Santa Clara, CA |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
160-162 |
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Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
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Abstract |
The scalability potential of low resistivity ternary metallic alloys (MAX) as an interconnect medium has been benchmarked against copper through first-principle simulations. We report that some carbon and nitrogen MAX phases have the potential to display a reduced sensitivity of their intrinsic resistivity to scaling, while showing improved electromigration properties. |
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Place of Publication |
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Wos |
000468672900053 |
Publication Date |
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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 |
978-1-5386-4337-2; 978-1-5386-4337-2 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
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:160474 |
Serial |
8219 |
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Permanent link to this record |