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

被引：31

作者：

Chu, Zhaodong ^{[1
]}

Wang, Chun-Yuan ^{[1
]}

Quan, Jiamin ^{[1
]}

Zhang, Chenhui ^{[2
]}

Lei, Chao ^{[1
]}

Han, Ali ^{[2
]}

Ma, Xuejian ^{[1
]}

Tang, Hao-Ling ^{[2
]}

Abeysinghe, Dishan ^{[1
]}

Staab, Matthew ^{[1
]}

Zhang, Xixiang ^{[2
]}

MacDonald, Allan H. ^{[1
]}

Tung, Vincent ^{[2
]}

Li, Xiaoqin ^{[1
]}

Shih, Chih-Kang ^{[1
]}

Lai, Keji ^{[1
]}

机构：

[1] Univ Texas Austin, Dept Phys, Austin, TX 78712 USA

[2] King Abdullah Univ Sci & Technol, Phys Sci & Engn Div, Thuwal 239556900, Saudi Arabia

来源：

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA | 2020年 / 117卷 / 25期

关键词：

transition-metal dichalcogenides; defects; charge carriers; spatiotemporal dynamics; laser-illuminated microwave impedance; microscopy; FIELD-EFFECT TRANSISTORS; FEW-LAYER MOS2; PHOTOLUMINESCENCE; EMITTERS; LIGHT;

D O I：

10.1073/pnas.2004106117

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

The optoelectronic properties of atomically thin transition -metal dichalcogenides are strongly correlated with the presence of de- fects in the materials, which are not necessarily detrimental for certain applications. For instance, defects can lead to an enhanced photoconduction, a complicated process involving charge genera- tion and recombination in the time domain and carrier transport in the spatial domain. Here, we report the simultaneous spatial and temporal photoconductivity imaging in two types of WS 2 mono - layers by laser -illuminated microwave impedance microscopy. The diffusion length and carrier lifetime were directly extracted from the spatial profile and temporal relaxation of microwave signals, respectively. Time -resolved experiments indicate that the critical process for photoexcited carriers is the escape of holes from trap states, which prolongs the apparent lifetime of mobile electrons in the conduction band. As a result, counterintuitively, the long-lived photoconductivity signal is higher in chemical -vapor deposited (CVD) samples than exfoliated monolayers due to the presence of traps that inhibits recombination. Our work reveals the intrinsic time and length scales of electrical response to photoexcitation in van der Waals materials, which is essential for their applications in optoelectronic devices.

引用

页码：13908 / 13913

页数：6

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