Zinc sulfide based thin film photodetector prepared by spray pyrolysis

The chemical spray pyrolysis technique was used to synthesis zinc sulfide (ZnS) thin films without annealing treatment. The thin films were grown on a glass substrate under various Zn:S ratios (1:1,1:2, 1:3). The spray solution was prepared by combining zinc acetate dihydrate and thiourea as precursor materials for Zn2+ and S2- ions, with deionized water serving as the solvent. The results of the ZnS film on glass showed a well-characterized thin film acquired using Zn:S of (1:1,1:2,1:3) molar ratio, nozzle to substrate distance (NSD) of 30 cm and a substrate temperature of 300 °C. Strong peaks (111) were obtained for all samples via X-ray diffraction analysis. The photoluminescence spectrum showed three distinctive peaks at roughly 2.36, 2.98, and 3.6 eV and the energy gap of the synthesized thin film was 3.66 eV. The MSM photodetectors (PDs) made from the layers on glass substrate showed response to UV illumination (400 nm), exhibiting a photosensitivity of 665% at base voltage of 3 V.