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 selfpowered characteristics. Compared with Sb2Se3/Si heterojunction, the response time of Sb2Se3/Cu2S/Si is significantly improved from 207 mu s to 160 mu s at 450 nm, from 117 mu s to 53 mu s at 638 nm, and it can reach up to 37 mu s 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.