P-type ZnO films deposited by DC reactive magnetron sputtering using codoping process

Abstract

P-type ZnO:Al:N thin films have been successfully deposited on Corning glass substrates using an industrial compatible, direct current sputtering technique. Effects of the nitrogen flow rate on the film structure and optoelectronic properties are investigated using X-ray diffraction measurement (XRD) and scanning electron microscopy. The XRD patterns suggest that all of the samples exhibit a preferential growth direction along the c-axis orientation and the change of film stress as the nitrogen flow increases. The Hall-effect measurements reveal that our samples are hole conduction (p-type), with high carrier concentration and low film resistivity. The UV–Vis spectroscopy measurements indicate that, as the nitrogen doping increases, the surface roughness increases, which significantly reduces the optical transmittance. For the purpose of demonstration, ZnO-based pn junctions have been fabricated and characterized by current–voltage measurements. It is shown that these fabricated devices exhibit a rectifying behaviour and, as a result, confirm the p-type conductivity.