Schottky diode fabrication via cold substrate evaporated ag on sol-gel derived ZnO ultra-thin films for semiconductor devices

Abstract

ZnO thin films were grown on glass and SnO2 substrate by using Sol-gel method with a simple, low cost-temperature and high controlled away. ZnO thin films were contacted with Ag in two different temperatures at 200K (cold substrate) and 300K (room temperature) by PVD Cold Substrate Method. Characterization of the obtained films and Schottky diodes studied by XRD, SEM, Optical and Electrical measurements. The average particle size and film thickness of the films were calculated as ~25 and ~300nm. Bandgap of the ZnO films coated on different substrates was calculated to be around 3.29-3.31 eV. Peaks of various types of defects were observed in different wavelengths from photoluminescence measurements. The barrier height and ideal factor values of Ag/ZnO Schottky diodes at 200K and 300K were (0.48-0.43eV; 15.60) and (0.66-0.15eV; 8.6-7.41), respectively. The series resistance values (4.46ω 4.88ω) at 200K and (3.65ω 4.78ω) at 300K were obtained from two different methods, respectively. Diodes made at 200K temperature were found to have a higher ideality factor. However, while 75% of all produced Schottky diodes at 200K substrate temperature show rectifying feature, this rate is only 25% in contacts made at 300K substrate temperature.