High-performance near-infrared PtSe2/n-Ge heterojunction photodetector with ultrathin Al2O3 passivation interlayer

• Published in: Science China materials Vol. 66; no. 7; pp. 2777 - 2787
• Main Authors: Zhu, Qinghai, Chen, Yexin, Zhu, Xiaodong, Sun, Yijun, Cheng, Zhiyuan, Xu, Jing, Xu, Mingsheng
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.07.2023; Springer Nature B.V
• Subjects: Aluminum oxide; Broadband; Chemistry and Materials Science; Chemistry/Food Science; Electric fields; Heterojunctions; Illumination; Infrared imaging; Interlayers; Materials Science; Optoelectronic devices; Passivity; Photometers; Room temperature; Two dimensional materials; near-infrared photodetector; germanium; passivation layer; 2D PtSe
• ISSN: 2095-8226; 2199-4501
• DOI: 10.1007/s40843-022-2402-3

Two-dimensional (2D) materials are being intensively exploited for broadband-responsive photodetectors (PDs). However, the broadband-responsive PDs based on 2D materials normally suffer from poor response to infrared wavelengths. Here, we report the excellent photoresponse performance of vertical PtSe 2 /ultrathin Al 2 O 3 /Ge PD under near-infrared illumination. We directly selenize Pt film deposited on Al 2 O 3 /Ge to form PtSe 2 layer. The ultrathin Al 2 O 3 passivation layer plays the role of surface modification, effectively weakening recombination of the photogenerated carriers. Under 1550-nm illumination, the PtSe 2 /ultrathin Al 2 O 3 /Ge PD with a working area of 50 µm × 50 µm at zero bias obtains a large responsivity of 4.09 A W −1 , and fast rise/fall times of 32.6/18.9 µs, respectively. And under an external electric field of −5 V, the responsivity and response speed of the PtSe 2 /ultrathin Al 2 O 3 /Ge PD can be as high as 38.18 A W −1 and as fast as 9.6/7.7 µs, respectively. We find that the working area has a great influence on the photoresponse characteristics. Furthermore, we demonstrate the PtSe 2 /ultrathin Al 2 O 3 /Ge PDs array shows outstanding violet, visible, and infrared imaging capability at room temperature. Our study suggests that the PtSe 2 /ultrathin Al 2 O 3 /Ge heterojunction has great application prospects for the design of emerging broadband optoelectronic devices with superior performance for near-infrared response.