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.