Characterization of zinc selenide-based ultraviolet detectors

Abstract

Wide bandgap semiconductors such as Zinc Selenide (ZnSe) have become popular for ultraviolet (UV) photodetectors. ZnSe has a higher photosensitivity compared to silicon-based detectors due to its larger bandgap. Its capability of turning optical power into valuable electrical signals makes it suitable for measurement and recording of UV exposure for military personnel. The prospect of ZnSe's unique medical and military applications has been the driving force of this study. This thesis presents characterization of performance of UV detectors using ZnSe-based Schottky diodes. There are a total of 15 photodetectors involved in this study. Three sets, each consisting of five photodetectors, were designed to detect Ultraviolet-A (320-400 nm), Ultraviolet-B (290-320 nm) and combination of both (UV-A and UV-B) wavelength ranges. The 15 detectors were analyzed for their photosensitivity using a photocurrent measurement system. Each diode's responsivity (ampere per watt) was determined as a function of wavelength of the incident radiation. The second part of the characterization process includes the determination of the current-voltage (IV) characteristics of the photodetectors. Each photodiode's current response was plotted as a function of both reverse and forward biased voltages and compared with the expected behavior.