An Ultrasensitive ReSe 2 /WSe 2 Heterojunction Photodetector Enabled by Gate Modulation and its Development in Polarization State Identification

Ultrasensitive photodetectors with polarization angle recognition have broad applications in both civilian and military domains. The emerging 2D materials with in‐plane anisotropy offer promising platforms for realizing these applications, owing to their intriguing properties. However, the lack of an effective photoconductivity gain mechanism and the low photocurrent anisotropic ratio have made it challenging to achieve digital output of polarization information. Herein, a gate voltage‐dependent phototransistor based on ReSe 2 /WSe 2 out‐of‐plane heterostructure is proposed. Attributed to sophisticated band alignment engineering, the device exhibits remarkable photoresponse characteristics and polarization sensitivity, including an outstanding responsivity of 2.29 × 10 4 A W −1 , an extraordinary detectivity of 5.65 × 10 13 Jones, a prompt rise/decay time of 197/182 µs, as well as a high photocurrent anisotropic ratio of 10.9. Based on these features, the device is integrated into a polarization recognition system, which accurately identifies the polarization angle of the incident light and displays it. These results demonstrate the strong potential of the ReSe 2 /WSe 2 device for future applications in polarization optical communication and logic circuits.