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Photoinduced Schottky Barrier Lowering in 2D Monolayer WS 2 Photodetectors
Author(s) -
Fan Ye,
Zhou Yingqiu,
Wang Xiaochen,
Tan Haijie,
Rong Youmin,
Warner Jamie H.
Publication year - 2016
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201600221
Subject(s) - materials science , monolayer , schottky barrier , photodetector , optoelectronics , photocurrent , chemical vapor deposition , equivalent series resistance , semiconductor , schottky diode , contact resistance , electrode , nanotechnology , layer (electronics) , voltage , chemistry , physics , diode , quantum mechanics
Arrays of metal–semiconductor–metal (MSM) photodetectors are fabricated using chemical vapor deposition (CVD) grown 2D monolayer WS 2 as the absorbing semiconductor (WS 2 ) with gold electrodes. A study of the channel length dependence (0.2–6.4 μm) on the photoresponsivity and gain show substantial increase in performance is achieved when the length is reduced to 200 nm. A large gain factor of up to 480 is measured for 200 nm length devices and attributed to lowering of the Schottky barriers due to the filling of trapped states between the metal contact and WS 2 by photogenerated carriers. Only photoexcited carriers close to the interface contribute to filling trap states and lowering the Schottky barrier and therefore increasing channel length only adds series resistance to the device that reduces performance. These results reveal detailed insights regarding the mechanisms for photocurrent generation in lateral MSM photodetectors that employ CVD grown monolayer WS 2 material, which has important consequences for the commercial applications and large scale development of 2D imaging arrays.