Effects of Hydrogen Dilution on ZnO Thin Films Fabricated via Nitrogen-Mediated Crystallization

Abstract

Hydrogenated ZnO thin films have been successfully deposited on glass substrates via a nitrogen mediated crystallization (NMC) method utilizing RF sputtering. Here we aim to study the crystallinity and electrical properties of hydrogenated NMC-ZnO films in correlation with substrate temperature and H 2 flow rate. XRD measurements reveal that all the deposited films exhibit strongly preferred (001) orientation. The integral breadth of the (002) peak from the hydrogenated NMC-ZnO films is smaller than that of the conventional hydrogenated ZnO films fabricated without nitrogen. Furthermore, the crystallinity and surface morphology of the hydrogenated NMC-ZnO films are improved by increasing substrate temperature to 400 °C, where the smallest integral breadth of (002) 2θ–ω scans of 0.83° has been obtained. By utilizing the hydrogenated NMC-ZnO films as buffer layers, the crystallinity of ZnO:Al (AZO) films is also improved. The resistivity of AZO films on NMC-ZnO buffer layers decreases with increasing H 2 flow rate during the sputter deposition of buffer layers from 0 to 5 sccm. At a H 2 flow rate of 5 sccm, 20-nm-thick AZO films with low resistivity of 1.5×10 -3 Ω cm have been obtained.