Ultrabroadband and High-Detectivity Photodetector Based on WS2/Ge Heterojunction through Defect Engineering and Interface Passivation

Broadband photodetectors are of great importance for numerous optoelectronic applications. Two-dimensional (2D) tungsten disulfide (WS2), an important family member of transition-metal dichalcogenides (TMDs), has shown great potential for high-sensitivity photodetection due to its extraordinary prop...

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Bibliographic Details
Published in:ACS nano Vol. 15; no. 6; pp. 10119 - 10129
Main Authors: Wu, Di, Guo, Jiawen, Wang, Chaoqiang, Ren, Xiaoyan, Chen, Yongsheng, Lin, Pei, Zeng, Longhui, Shi, Zhifeng, Li, Xin Jian, Shan, Chong-Xin, Jie, Jiansheng
Format: Journal Article
Language:English
Published: American Chemical Society 22.06.2021
Subjects:
interface passivation
broadband photodetectors
2D WS2 layers
defect engineering
mid-wave infrared
ISSN:1936-0851, 1936-086X, 1936-086X
Online Access:Get full text
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Summary:Broadband photodetectors are of great importance for numerous optoelectronic applications. Two-dimensional (2D) tungsten disulfide (WS2), an important family member of transition-metal dichalcogenides (TMDs), has shown great potential for high-sensitivity photodetection due to its extraordinary properties. However, the inherent large bandgap of WS2 and the strong interface recombination impede the actualization of high-sensitivity broadband photodetectors. Here, we demonstrate the fabrication of an ultrabroadband WS2/Ge heterojunction photodetector through defect engineering and interface passivation. Thanks to the narrowed bandgap of WS2 induced by the vacancy defects, the effective surface modification with an ultrathin AlO x layer, and the well-designed vertical n–n heterojunction structure, the WS2/AlO x /Ge photodetector exhibits an excellent device performance in terms of a high responsivity of 634.5 mA/W, a large specific detectivity up to 4.3 × 1011 Jones, and an ultrafast response speed. Significantly, the device possesses an ultrawide spectral response spanning from deep ultraviolet (200 nm) to mid-wave infrared (MWIR) of 4.6 μm, along with a superior MWIR imaging capability at room temperature. The detection range has surpassed the WS2-based photodetectors in previous reports and is among the broadest for TMD-based photodetectors. Our work provides a strategy for the fabrication of high-performance ultrabroadband photodetectors based on 2D TMD materials.
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ISSN:1936-0851
1936-086X
1936-086X
DOI:10.1021/acsnano.1c02007