Promoting Photosensitivity and Detectivity of the Bi/Si Heterojunction Photodetector by Inserting a WS2 Layer

• Published in: ACS applied materials & interfaces 2015-12, Vol.7 (48), p.26701-26708
• Main Authors: Yao, Jiandong, Zheng, Zhaoqiang, Shao, Jianmei, Yang, Guowei
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b08677

Layered transition metal dichalcogenides (TMDs) have been proven to be essential building blocks for the high-performance optoelectronic devices as a result of their favorable bandgaps, extraordinary light absorption, and closed surface electronic structures. However, the in-depth exploration of their operating mechanism as insertion layers in heterojunction photodetectors is scarce. Here, we demonstrate that a Bi/Si heterojunction photodetector can achieve a superior performance by inserting a WS2 layer. A high photosensitivity of 1.4 × 108 cm2/W and an outstanding detectivity of 1.36 × 1013 cm Hz1/2 W–1 are obtained, which are comparable or even surpass those of state-of-art commercial photodetectors. The working mechanism of the Bi/WS2/Si sandwich-structured photodetector is unveiled, including the efficient passivation of the interface, enhancement of light absorption, and selective carrier blocking. Finally, a good voltage tunability of the photoresponse is also demonstrated. These findings are significant to the deep understanding on the integration of layered TMDs with conventional semiconductors, and they provide an attractive methodology to develop layered TMDs in a multi-junction system.