2016 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, ナノエレクトロニクス研究部門, 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 / topological insulators / dichalcogenides / heterostrictures |
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| Outline of Annual Research Achievements |
In the first year of the project, a dedicated computer system has been built and software installed.
We demonstrated that there exists a previously unknown phase of MoTe2, that is formed in the electronically excited state due to population inversion. This phase, which is unstable and decays to the ground 2H state after cessation of the excitation, is metallic and can act to lower the energy barrier on the way to the metastable 1T′ phase. The result was published in Phys. Rev. B.
The bulk band structures of artificially constructed van der Waals chalcogenide heterostructures were systematically examined using DFT simulations. The use of a modified Becke-Johnson functional demonstrated that a Dirac cone is formed when tensile stress is applied to a GeTe/Sb2Te3 heterostructure and the band gap can be increased by tuning the stress. A manuscript was submitted to ACS Applied Materials & Interfaces
Through DFT simulationsMoS2 has been shown to be a suitable substrate for epitaxial growth of few-monolayer GaN that allows the formation of a Haeckelite phase due to a weak van der Waals interaction between GaN and MoS2. A manuscript was submitted to Physical Review Materials.
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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
We are making reasonable progress in the proposed study of transition letal dichalcogenides, phase-change alloys and chalcogenide-based van der Waals heterostructures
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| Strategy for Future Research Activity |
In the coming year, we shall continue the DFT study of chalcogenide layered materials and heterostructures thereof. In particular, we shall concentrate on the effects of surface termination and heterostructures between topological insulators and dichalcogenides. Based on the last year finding that GaN can form few-layer Haeckelite structures in combination with MoS2 due to the weak van der Waals interaction that prevent the formation of the wurtzite phase, we shall further explore the possibilities offered by the presence of a van der Waals gap in these structures.
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| Causes of Carryover |
We were not sure if there will be a publication charge for the Phys. Rev. B paper published and hence we could not buy the needed memory upgrade that would allow us to perform heavier simulations
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| Expenditure Plan for Carryover Budget |
Memory upgrade for the computer system
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