Aging and Annealing Effects of ZnO Thin Films on GaAs Substrates Deposited by Pulsed Laser Deposition

摘要

Zinc oxide (ZnO) thin films were deposited on GaAs (100) substrates at different temperatures in the pulsed laser deposition (PLD) system. From the measurements of X-ray diffraction (XRD) at room temperature, 300-500℃ were found to be good condition for the crystallization of the thin films. From the photoluminescence (PL) measurements, 500℃ was found to be the optimized temperature for its optical property. Samples grown at 100, 200,300, and 400℃ showed near band-edge (NBE) emissions and deep-level emissions. The intensity of deep-level emissions decreased as time goes on, which is believed to originate from oxygen vacancies or zinc interstitials in thin films. While for the sample grown at 500℃, bright NBE emissions were observed at room temperature, and no deep-level emissions observed. This means that the high-optical-quality thin film was grown at 500℃. At the same time, annealing process of ZnO thin films grown at room temperature was carried out in PLD chamber. It was found that the annealing temperature of 600℃ has strong effects on its PL. Aging and annealing effects in ZnO thin films grown on GaAs substrates by PLD were observed for the first time.