Strain Effects on Excitonic Photoluminescence in 2D Transition-Metal Dichalcogenides

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05051
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: The University of Tokyo
• Principal Investigator: UCHIDA KAZUHITO 東京大学, 物性研究所, 技術専門員 (20422438)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 薄膜 / 歪み / 遷移金属ダイカルコゲナイド / 励起子ホール効果

Outline of Final Research Achievements

We have developed a strain control method, which is the core technology of this research, in which the suspended thin film is vibrated in a liquid medium and the in-plane strain in the film is controlled by the drag force resulting from pressure difference between the upper and lower surfaces of the film. Furthermore, vibration-in-liquid experiment in which a suspended foil strain gauge was immersed in fluorine-based inert liquid, revealed that strain gauge signal well synchronized with input signal over the frequency range from 1 to 50 Hz, confirming the generation of strain. We also developed a micro-photoluminescence imaging device for thin film vibrating in liquid, and fabricated suspended single-layer and multi-layer MoS2/h-BN/PMMA thin films. Finally we constructed a phase-sensitive imaging system by detecting the time modulation of both strain and light polarization.

Free Research Field

物性物理

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した架橋化薄膜の歪み制御技術は、全く新しい発想に基づいており、特長として、第一に、薄膜に加える歪みの強さ、周波数（歪みの時間変化）が容易に制御可能な点、第二に、基板開孔部の形状により、一軸性や非一様性など、歪みの空間対称性を自在に制御できる点、そして第三に、歪みが周期的に変動することから位相検波的手法による高感度測定が可能な点が挙げられる。歪みによる励起子あるいは電子状態の制御は「バレートロニクス」実現へ向けた一つの重要なアプローチであり、薄膜あるいは原子層物質における物性研究の新たな手法を提案できると考えている。