Tunable self-powered n-SrTiO3 photodetectors based on varying CuS-ZnS nanocomposite film (p-CuZnS, p-CuS, and n-ZnS)

The heterojunction photodetector between n-SrTiO3(n-STO)and p-CuS-ZnS(p-CZS)is prepared by a simple chemical bath deposition.The p-CZS/n-STO photodetector exhibits excellent self-powered characteristics under 390-nm light illumination,including high photosensitivity(on/off ratio of 300),fast response speed(0.7/94.6 ms),and good wavelength selectivity(410-380 nm).More importantly,the self-powered n-STO photodetectors can be regulated by varying the composition of CZS film(p-CZS,p-CuS,and n-ZnS).All devices exhibit a large opencircuit voltage and show different self-powered behaviors because of the different built-in electric fields.The open-circuit voltages of the CZS/STO,CuS/STO,and ZnS/STO devices are measured to be 0.56,0.30,and 0.35 V,respectively.This work provides a simple and effective way to fabricate tunable self-powered photodetectors by varying the composition of the nanocomposite film.