Unveiling defect-mediated carrier dynamics in monolayer semiconductors by spatiotemporal microwave imaging

• DOI: 10.1073/pnas.2004106117
• Publication Date: 2020-06-09T00:35:06Z
• Authors: Zhaodong Chu; Chun-Yuan Wang; Jiamin Quan; Chenhui Zhang; Chao Lei; Ali Han; Xuejian Ma; Hao-Ling Tang; Dishan Abeysinghe; Matthew Staab; Xixiang Zhang; Allan H. MacDonald; Vincent Tung; Xiaoqin Li; Chih-Kang Shih; Keji Lai
• Keywords: Photoexcitation; Photoconductivity; Charge carrier

Significance Defects in two-dimensional (2D) transition-metal dichalcogenides play a crucial role controlling the spatiotemporal dynamics of photogenerated charge carriers, which remain poorly understood to date. In this paper, defect-mediated carrier diffusion and recombination WS 2 monolayers are quantitatively investigated by laser-illuminated microwave impedance microscopy. Surprisingly, photoresponse is general stronger more disordered regions samples. Such counterintuitive observations reconciled spatiotemporally resolved experiments, indicate that electron lifetime prolonged due slow release holes from trap states. The results reveal intrinsic time length scales photocarriers van der Waals materials, providing guidance for implementing nanooptoelectronic devices based on 2D semiconductors.