ReS<sub>2</sub> Nanosheet/WS<sub>2</sub> Nanosheet/p-GaN Substrate Dual Junction Photodetectors
Quansheng Zheng, Zhicong Qiu, Qiyang Zhang, Mengmeng Yang, Jianpeng Lei, Lixiang Han, Li‐Ming Tang, Zhaoqiang Zheng, Xiaozhou Wang, Jingbo Li
Abstract
The broad application of ultraviolet (UV) photodetectors in civil, astronomical, and military fields has sparked significant research interest. Recently, two-dimensional layered transition metal dichalcogenides have emerged as an ideal platform for developing high-performance and versatile photodetectors due to their abundant intriguing optoelectronic properties. Here, we constructed a photodetector utilizing dual heterojunctions based on rhenium disulfide (ReS 2 ) nanosheet/tungsten disulfide (WS 2 ) nanosheet/p-type gallium nitride (p-GaN) substrate, which incorporate dual built-in electric fields. The built-in electric field at the WS 2 –p-GaN interface accelerates the separation of photogenerated electrons, enabling a fast photoresponse. Simultaneously, the built-in electric field at the ReS 2 –WS 2 interface not only suppresses dark current but also confines photoexcited holes within the ReS 2 layer, ultimately extending the lifetime of photocarriers. Consequently, a photogating effect with high photoconductive gain is achieved. Exploiting these advantages, the ReS 2 /WS 2 /p-GaN device exhibits a high responsivity of 3.78 A/W, an outstanding detectivity of 2.1 × 10 12 Jones, and a fast rise/decay time of 259/374 μs under 365 nm light with a power density of 0.069 mW/cm 2 . Furthermore, the device demonstrates its potential for high-resolution UV imaging by functioning as a single pixel, showcasing its capabilities for advanced UV detection and imaging applications.