Probing photosensor response of the Ag/n-ZnS/p-Si heterojunctions at different ZnS thin film thicknesses

The present work aims at the evaluation of the electrical and photoelectrical properties of Ag/n-ZnS/p-Si as a function of ZnS film thickness. The surface morphologies of ZnS thin films were found to be homogenous and devoid of cracks. Additionally, it was observed that the roughness increased with the thickness of thin films. While X-ray diffraction (XRD) data confirmed the amorphous nature of sputtered ZnS thin films, Fourier transform infrared (FTIR) spectra exhibited characteristic ZnS peaks. The optical band gap of ZnS thin films was determined to be 3.7 eV. In addition, the Ag/ZnS/p-Si structures exhibited strong rectifying properties. The existence of a correlation between the rise in thickness of ZnS and the decrease in barrier height as well as the increase in series resistance, was demonstrated from current-voltage (I-V) data obtained in the dark. The I-V measurements were also effectively conducted at different light intensities to demonstrate their photosensitive attributes. It was reported the photosensitivity of devices increased with the increase in applied light power and demonstrated the photosensor behavior of Ag/ZnS/p-Si heterojunctions.