Zener Tunneling and Photoresponse of a WS2/Si van der Waals Heterojunction

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• 作者：Changyong Lan ; Chun Li ; Shuai Wang ; Tianying He ; Tianpeng Jiao ; Dapeng Wei ; Wenkui Jing ; Luying Li ; Yong Liu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：July 20, 2016
• 年：2016
• 卷：8
• 期：28
• 页码：18375-18382
• 全文大小：586K
• 年卷期：0
• ISSN：1944-8252

文摘

Van der Waals heterostructures built from two-dimensional materials on a conventional semiconductor offer novel electronic and optoelectronic properties for next-generation information devices. Here we report that by simply stacking a vapor-phase-synthesized multilayer n-type WS₂ film onto a p-type Si substrate, a high-responsivity Zener photodiode can be achieved. We find that above a small reverse threshold voltage of 0.5 V, the fabricated heterojunction exhibits Zener tunneling behavior which was confirmed by its negative temperature coefficient of the breakdown voltage. The WS₂/Si heterojunction working in the Zener breakdown regime shows a stable and linear photoresponse, a broadband photoresponse ranging from 340 to 1100 nm with a maximum photoresponsivity of 5.7 A/W at 660 nm and a fast response speed of 670 μs. Such high performance can be attributed to the ultrathin depletion layer involved in the WS₂/Si p–n junction, on which a strong electric field can be created even with a small reverse voltage and thereby enabling an efficient separation of the photogenerated electron–hole pairs.