Self-powered Filterless Narrow-band p-n Heterojunction Photodetector for Low Background Limited Near-infrared Image Sensor Application.

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 self-driving effect inherent to p-n junction is very attractive in optic-electronic integration, the application of p-n junction in narrow-band photodetector 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 bandgap 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 image system based on the narrowband CuGaTe2/Si photodetector showed high noise immunity for its spectral selective characteristics. .