Self-powered photodetector with fast response based on Sb2Se3/Cu2S/Si heterojunction

Antimony selenide (Sb2Se3) thin film, as a potential semiconductor material, has good photoelectric response in the visible and near-infrared regions and excellent application prospects in wide-spectrum detectors. In the present work, copper sulfide (Cu2S) film was inserted to improve the separation and migration of photogenerated carriers in Sb2Se3 film. Sb2Se3 and Sb2Se3/Cu2S thin films were deposited on n-type silicon wafers using thermal evaporation. Excellent optical response and stable switching ratios at 638 nm and 980 nm can be obtained for the photodetectors based on Sb2Se3/Si and Sb2Se3/Cu2S/Si heterojunctions. The Cu2S film as mid-layer has increased on/off ratio from 119 to 155 (638 nm) and 265 to 510 (980 nm), respectively. The devices have good self-powered characteristics. Compared with Sb2Se3/Si heterojunction, the response time of Sb2Se3/Cu2S/Si is significantly improved from 207 μs to 160 μs at 450 nm, from 117 μs to 53 μs at 638 nm, and it can reach up to 37 μs at 980 nm. The sandwiched p-type Cu2S can effectively enhance the separation and migration of the photogenerated carriers by the large driving force of built-in field at the heterointerface. The Sb2Se3/Cu2S/Si photodetector has a potential application in wide-spectrum-detection field.