Spray pyrolysis deposited zinc oxide on p-silicon substrates for ultraviolet photodetector applications
Abstract
An ultraviolet (UV) photodiode was fabricated using undoped zinc oxide (ZnO) on p-silicon (Si) substrate. ZnO films were deposited using spray pyrolysis technique on p-Si and glass substrates with varying volume of precursor solution (15, 30, 45, 60 and 90 mL). The XRD profile of the 60 mL sample confirmed the successful growth of ZnO wurtzite structure. The transmittance spectra of ZnO films on glass substrates were highly transparent at the visible region (65-94% at 450 nm). The calculated band gap of the samples using Tauc approximation ranged from 3.29-3.25 eV. Approximation of film thickness using the oscillations in reflectance spectra revealed higher volume of precursor solution sprayed resulted to thicker films. The IV curve measurements of n-ZnO/p-Si photodiode samples showed a decrease in resistance in the third quadrant by around 51-88% when illuminated with UV light, demonstrating their ability to detect UV light.
