Study of Optical and Electrical Properties of RF-Sputtered ZnSe/ZnTe Heterojunctions for Sensing Applications

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical electrical characterization was performed. Onto an glass substrate, 100 nm gold (Au) thin film deposited Thermal Vacuum Evaporation (TVE) representing the back-contact, followed successive RF-MS deposition of ZnTe, ZnSe, Oxide (ZnO) Indium Tin (ITO) films, finally resulting in Au/ZnTe/ZnSe/ZnO/ITO sub-micrometric “substrate”-type configuration. Next, Ultraviolet-Visible (UV-VIS) spectroscopy performed component band gap values determined. The measurements dark under illumination at different light intensities subsequently Current–Voltage (I–V) characteristics are nonlinear with a relatively high asymmetry, following modified Shockley–Read equation. From analysis, series resistance, shunt ideality factor saturation current determined accuracy. It is worth noting that action spectrum structure shifted to short wavelengths. A sensibility test for 420–500 range while changing intensity incident from mW/cm2 down 10 measuring photocurrent. obtained results provided sufficient information consider present n-ZnSe/p-ZnTe be more suitable UV domain, demonstrating potential integration within photodetectors relying environmentally-friendly materials.