Study on electronic properties of two-dimensional layered materials under high electric field

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05500
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Okayama University
• Principal Investigator: Goto Hidenori 岡山大学, 異分野基礎科学研究所, 准教授 (90322669)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: グラフェン / 電界効果 / 二次元層状物質 / バンド制御 / イオン液体 / 電子移動 / 自己組織化単分子膜 / 分子吸着

Outline of Final Research Achievements

Purpose of this study is to investigate electronic properties of two-dimensional materials (2DMs) under perpendicular electric field. To produce large homogeneous electric field, we have combined electron transfer method and electrostatic gating method. Using mono-/bi-layer graphene, we found that electron-transfer molecules produced inhomogeneous electric field and degraded the mobility. These disadvantages were solved as follows. First, the ionic liquid gate enabled us to produce homogeneous electric field because the movable ions were arranged to suppress the inhomogeneity. Next, molecules with high symmetry and small size had a tendency not to decrease the mobility. Furthermore, unique electric-field effect was found in doped topological insulator in which the mobility depended on the direction of the electric field.
Our findings are useful for inducing novel electronic phenomena and producing multi-functional 2DM devices under electric field.

Free Research Field

物性物理学

Academic Significance and Societal Importance of the Research Achievements

電界下における電子物性の研究には、トポロジカル物質における新規電磁現象のように、未踏の領域が広く残っている。その研究のためには、強く一様な電界の発生方法を開発することが必要である。電子移動および電界効果の2つの方法を用いたわれわれの研究成果により、この課題を解決する方針が見いだされた。これにより、二次元層状物質における新規電子物性の開拓や、自由度の高い電界制御による新たな多機能デバイスの創出が期待される。