Self-Powered Filterless Narrow-Band p–n Heterojunction Photodetector for Low Background Limited Near-Infrared Image Sensor Application

Abstract

Photonic detection with narrow spectrum selectivity is very important to eliminate the signal from obtrusive light, which can improve the anti-interference ability of the infrared imaging system. While the self-driving effect inherent to the p-n junction is very attractive in optic-electronic integration, the application of the p-n junction in narrow-band photodetectors is limited by the usual broad absorption range. In this work, a self-powered filterless narrowband near-infrared photodetector based on CuGaTe₂/silicon p-n junction was reported. The as-fabricated photodetector exhibited typical narrow-band response which shall be ascribed to the slightly smaller band gap of Si than CuGaTe₂ and the restricted photocurrent generation region in the p-n heterojunction by optimizing CuGaTe₂ thickness. It is observed that when the thickness of CuGaTe₂ film is 143 nm, the device exhibits a response peak centered around 1050 nm with a full-width at half-maximum of ∼118 nm. Further device analysis reveals a specific detectivity of ∼10¹² Jones and a responsivity of 114 mA/W under 1064 nm illumination at zero bias. It was also found that an image system based on the narrowband CuGaTe₂/Si photodetector showed high noise immunity for its spectral selective characteristics.