  Photoluminescence (PL) spectra of zinc oxide (ZnO) samples with different hydrogen peroxide (H2O2) treatment durations were measured to examine several point defects on the surface of the films. These results suggest successful oxidation through the reaction between oxygen radicals dissociated from H2O2 and the ZnO surface. To further confirm the defect induced gain mechanism, we fabricate highly transparent Schottky diodes, and measure the key diode characteristics. Photocurrents are measured under different wavelengths, and possible explanations of the high optical gain within the ultraviolet (UV) region are provided. 
Optical Properties of ITO/ZnO Schottky Diode with Enhanced UV   Photoresponse