Effects of UV illumination on oxygen detection for ZnO film prepared by thermally oxidized Zn on sapphire substrate

Abstract

The ZnO thin film prepared after the 600 degrees C oxidation of thermally-evaporated Zn thin film on sapphire substrate was studied. A nano structured surface morphology was observed by scanning electron microscope. With following Ti/Au metallization, the metal-semiconductor-metal (MSM) device was formed. With ultra violate (UV) light illumination come from the mercury lamp with a short pass filter, the device resistance variation under oxygen atmosphere was investigated. The reduction of detection response time and recovery time for this device with UV light illumination were observed also. After discussion based on the grain boundary connected model, the observed resistance variation controlled by the nano texture was realized. The UV light illumination technology shows an effective method to enhance the gas detection response time for this ZnO MSM gas sensor. Keywords: ZnO, MSM,