Spatially Bandgap-Graded MoS2(1−x)Se2x Homojunctions for Self-Powered Visible–Near-Infrared Phototransistors

Nano-Micro Letters

Zhengxiao Guo¹  Xiaoyu Han¹  Hao Xu²  Xiao Li²  Jiang Wu²  Huiyun Liu²  Wei Liu²  Gyeong Hee Ryu³  Wenshuo Xu³  Jamie H. Warner³  Caihong Li⁴  Guifu Zou⁵  Juntong Zhu⁵ 

[1] Department of Chemistry, University College London;Department of Electronic and Electrical Engineering, University College London;Department of Materials, University of Oxford;Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China;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;

关键词: Transition metal dichalcogenides;    Graded bandgaps;    Homojunctions;    Phototransistors;    Self-powered;   

DOI  :  10.1007/s40820-019-0361-2

来源: DOAJ

【 摘 要 】

Abstract 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 built-in 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 ~ 1011 Jones, and an on/off 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.

【 授权许可】

Unknown