Effects of H-2 annealing treatment on photoluminescence and structure of ZnO : Al/Al2O3 grown by radio-frequency magnetron sputtering

Abstract

Al-doped zinc oxide (AZO) thin films have been grown on Al2O3 (0001) substrate by radio-frequency (rf) magnetron sputtering at 550 degreesC. The AZO films have been annealed by a rapid thermal process in H-2 exposure with a temperature range of 600-1000 degreesC. Effects of hydrogen on the AZO films have been investigated using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The as-grown AZO film shows only broad deep defect-level PL. After annealing at 600 degreesC, deep defect-level emission is quenched and near-band-edge (NBE) emission is observed at around 382 nm (3.2 eV), which can be explained by the H-2 passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emissions have been observed for the first time in annealed AZO thin films. Incorporation of hydrogen and formation of oxygen deficient in annealed AZO films have been studied using XPS. Surface morphology and microstructure of AZO films have been carried out by SEM. (C) 2003 The Electrochemical Society.