Narrow-band Near Infrared Photodetector Based On CuGaTe₂/Si Pn Junction

Narrow-band photodetectors are widely used in surveillance,image sensing,defense application,and environment monitoring to eliminating the signal from obtrusive light.The application of p-n junction in narrow-band photodetector is limited by the usual broad absorption range,although it is very attractive in optic-electronic integration for the self-driving effect.Here we fabricated a self-powered filterless narrowband near-infrared light photodetector based on CuGaTe₂/silicon p-n junction.The realization of narrow-band response based on CuGaTe₂/silicon p-n junction should be ascribed to the slightly larger bandgap of CuGaTe₂compared with Si and the restricted photocurrent generation region in p-n junction tuned by CuGaTe₂film thickness.CuGaTe₂could act as a high spectrum selectivity“filter”for Si which is almost transparent to the photons with energy below its bandgap.And its spectral selectivity can be controlled by the thickness of CuGaTe₂film,due to the tuning of photocurrent generation region in CuGaTe₂/Si pn junction.Thus narrow-band photoresponse,centered around the bandgap of Si,could be achieved with optimum thickness CuGaTe₂ film.When the thickness of CuGaTe₂film is 143nm,the device exhibits a response peak centered around 1050 nm with a full-width at half-maximum of～118 nm.Benefited from the self-driving effect of p-n junction,the device has a responsivity（R）of 114 m A/W at zero bias,under 1064 nm light illumination.What’s more,the CuGaTe₂/silicon heterojunction device can markedly suppress the dark current,resulting in a large on/off ratio of≈10⁴and a high specific detectivity of～10¹²Jones.The image system based on the narrowband CuGaTe₂/Si photodetector showed high noise immunity for its spectral selective characteristics.The simple structure and Si-based heterostructure make it compatible with the microelectronic planar process based on Si,and has a broad application prospect in the field of optoelectronic integration.