2017 Fiscal Year Research-status Report
Ab-initio study of topological chalcogenide van-der-Waals heterostructures and superlattices
| Project/Area Number |
16K04896
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
Kolobov A. 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 首席研究員 (60357043)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | chalcogenides / van der Waals solids / electronic structure / strain control / superlattices |
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| Outline of Annual Research Achievements |
In the past fiscal year studies of chalcogenide van der Waals (vdW) superlattices were continued. The main results are as follows.
-For vdW interfacial phase-change memory we demonstrated that (1) the Kooi-like structure is obtained not as a result of Ge in-diffusion (as previously believed) but due to atomic plane reversal in the first SbTe bilayer. (2) reconfiguration of vdW gaps in GeTe-Sb2Te3 superlattices that involves Sb atoms leads to a semiconductor-metal transition that can be responsible for the experimentally observed switching. (3) Reconfiguration of vdW gaps was confirmed experimentally using e-beam exposure as acting stimulus.
-The bulk band structures of a variety of artificially constructed vdW chalcogenide heterostructures IVTe/ V2VI3 (IV: C, Si, Ge, Sn, Pb; V: As, Sb, Bi; VI: S, Se, Te) were examined and it was found that a Dirac cone is formed when tensile stress is applied to a GeTe/Sb2Te3 heterostructure, and the band gap can be controlled by tuning the stress.
-Sb2Te3/MoTe2 heterostructures/superlattices were studied and stress was shown to result in the overall metallic structure.
-Sb2Te3 slabs cut along different crystal orientations were studied and it was shown that while the slab obtained at vdW gaps did possess Dirac cones (as expected), slabs obtained by cutting the structure along generic directions underwent surface reconstruction resulting in the loss of Dirac cones.
-Strain was demonstrated to be an efficient tool to tune electronic structure of few-monolayer GaN, both free-standing and interacting with MoS2 through vdW forces.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The work is progressing smoothly although some problems were caused by the inability to use the internet and to access the computing cluster because of the problem with AIST server for more than a month.
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| Strategy for Future Research Activity |
In the coming year ab-initio studies of vdW superlattices and heterostructures will be continued. The main accent will be made on the role of stress and the nature of chalcogens in the covalently bonded blocks.
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Research Products
(5 results)
