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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 |
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Year  |
2020 |
Publication |
Physica Status Solidi-Rapid Research Letters |
Abbreviated Journal |
Phys Status Solidi-R |
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Issue |
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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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Wos |
000512431100001 |
Publication Date |
2020-01-28 |
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Series Issue |
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Edition |
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ISSN |
1862-6254 |
ISBN |
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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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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 |
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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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Wos |
000468672900051 |
Publication Date |
2018-09-06 |
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ISSN |
978-1-5386-4337-2; 978-1-5386-4337-2 |
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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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no |
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Call Number |
UA @ admin @ c:irua:160473 |
Serial |
7436 |
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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) |
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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 |
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978-1-72811-987-8; 978-1-72811-987-8 |
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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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Notes |
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no |
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Call Number |
UA @ admin @ c:irua:158694 |
Serial |
7942 |
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Author |
Kumar, A.; Kundu, S.; Samantaray, D.; Kundu, P.; Zanaga, D.; Bals, S.; Ravishankar, N. |
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Title |
Designing diameter-modulated heterostructure nanowires of PbTe/Te by controlled dewetting |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Nano letters |
Abbreviated Journal |
Nano Lett |
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Volume |
17 |
Issue |
17 |
Pages |
7226-7233 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
<script type='text/javascript'>document.write(unpmarked('Heterostructures consisting of semiconductors with controlled morphology and interfaces find applications in many fields. A range of axial, radial, and diameter-modulated nanostructures have been synthesized primarily using vapor phase methods. Here, we present a simple wet chemical routine to synthesize heterostructures of PbTe/Te using Te nanowires as templates. A morphology evolution study for the formation of these heterostructures has been performed. On the basis of these control experiments, a pathway for the formation of these nanostructures is proposed. Reduction of a Pb precursor to Pb on Te nanowire templates followed by interdiffusion of Pb/Te leads to the formation of a thin shell of PbTe on the Te wires. Controlled dewetting of the thin shell leads to the formation of cube-shaped PbTe that is periodically arranged on the Te wires. Using control experiments, we show that different reactions parameters like rate of addition of the reducing agent, concentration of Pb precursor and thickness of initial Te nanowire play a critical role in controlling the spacing between the PbTe cubes on the Te wires. Using simple surface energy arguments, we propose a mechanism for the formation of the hybrid. The principles presented are general and can be exploited for the synthesis of other nanoscale heterostructures.')); |
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Place of Publication |
Washington |
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Wos |
000418393300009 |
Publication Date |
2017-11-29 |
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Edition |
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ISSN |
1530-6984 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
12.712 |
Times cited |
11 |
Open Access |
OpenAccess |
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Notes |
; N.R acknowledges financial support from SERB, DST, Government of India. The authors acknowledge the electron microscopy facilities at the Advanced Facility for Microscopy and Microanalysis, IISc. S.B., P.K., and D.Z. acknowledge ERC Starting Grant 335078 COLOURATOMS for financial support. ; ecas_Sara |
Approved |
Most recent IF: 12.712 |
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Call Number |
UA @ lucian @ c:irua:148557UA @ admin @ c:irua:148557 |
Serial |
4870 |
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Author |
Kundu, S.; Kundu, P.; Van Tendeloo, G.; Ravishankar, N. |
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Title |
Au2Sx/CdS nanorods by cation exchange : mechanistic insights into the competition between cation-exchange and metal ion reduction |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Small |
Abbreviated Journal |
Small |
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Volume |
10 |
Issue |
19 |
Pages |
3895-3900 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Thumbnail image of graphical abstract It is well known that metals with higher electron affinity like Au tend to undergo reduction rather than cation-exchange. It is experimentally shown that under certain conditions cation-exchange is dominant over reduction. Thermodynamic calculation further consolidates the understanding and paves the way for better predictability of cation-exchange/reduction reactions for other systems. |
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Publisher |
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Place of Publication |
Weinheim |
Editor |
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Wos |
000344451900011 |
Publication Date |
2014-06-02 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
1613-6810; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.643 |
Times cited |
8 |
Open Access |
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Notes |
countatoms |
Approved |
Most recent IF: 8.643; 2014 IF: 8.368 |
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Call Number |
UA @ lucian @ c:irua:118010 |
Serial |
3514 |
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