Spatially Bandgap-Graded Mo S2（1-x）Se2x Homojunctions for Self-Powered Visible–Near-Infrared Phototransistors  

作　　者：Hao Xu Juntong Zhu Guifu Zou Wei Liu Xiao Li Caihong Li Gyeong Hee Ryu Wenshuo Xu Xiaoyu Han Zhengxiao Guo Jamie HWarner Jiang Wu Huiyun Liu 

机构地区：[1]Department of Electronic and Electrical Engineering,University College London,Torrington Place,London WC1E 7JE,UK [2]School of Energy,Soochow Institute for Energy and Materials Innovations,and Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province,Soochow University,Suzhou 215006,People’s Republic of China [3]London Centre for Nanotechnology,University College London,London WC1H 0AH,UK [4]Institute of Fundamental and Frontier Sciences,University of Electronic Science and Technology of China,Chengdu 610054,People’s Republic of China [5]Department of Materials,University of Oxford,Parks Road,Oxford OX13PH,UK [6]Department of Chemistry,University College London,20 Gordon St,Bloomsbury,London WC1H 0AJ,UK [7]Department of Chemistry,The University of Hong Kong,Pokfulam Road,Hong Kong,People’s Republic of China [8]Zhejiang Institute of Research and Innovation,The University of Hong Kong,Qingshan Lake SciTech City,Hangzhou,People’s Republic of China

出　　处：《Nano-Micro Letters》2020年第2期185-198,共14页纳微快报（英文版）

基　　金：supported by Grants from the UK EPSRC Future Compound Semiconductor Manufacturing Hub(EP/P006973/1);the financial support from EPSRC(EP/L018330/1,EP/N032888/1);the U.S.Army Research Laboratory under Cooperative Agreement Number W911NF-16-2-0120;the “973 Program—the National Basic Research Program of China” Special Funds for the Chief Young Scientis(2015CB358600);the Excellent Young Scholar Fund from National Natural Science Foundation of China(21422103);the China Scholarship Council(CSC)

摘　　要：Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features, which opens up new potential for device applications. Here, visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2（1-x）Se2x alloys, synthesized by a simple and controllable chemical solution deposition method, are reported. The graded bandgaps, arising from the spatial grading of Se composition and thickness within a single domain, are tuned from 1.83 to 1.73 e V, leading to the formation of a homojunction with a builtin electric field. Consequently, a strong and sensitive gate-modulatedphotovoltaic e ect is demonstrated, enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 m A W-1, a specific detectivity up to ～ 1011 Jones, and an on/o ratio up to ～ 104. Remarkably, when illuminated by the lights ranging from 405 to 808 nm, the biased devices yield a champion photoresponsivity of 191.5 A W-1, a specific detectivity up to ～ 1012 Jones, a photoconductive gain of 106–107, and a photoresponsive time in the order of ～ 50 ms. These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.

关 键 词：Transition metal dichalcogenides Graded bandgaps HOMOJUNCTIONS PHOTOTRANSISTORS SELF-POWERED 

分 类 号：O614.612[理学—无机化学]