Optical and structural characteristics of ZnO films grown on (0001) sapphire substrates by ALD using DEZn and N2O

Abstract

Zinc oxide (ZnO) films were grown at 600 degrees C on (0 0 0 1) sapphire substrates by atomic layer deposition (ALD) using diethylzinc (DEZn) and nitrous oxide (N2O) as source precursors. In some cases, low-temperature (LT) ZnO buffer layers were employed along with post-annealing or buffer-layer annealing for the optimization of ZnO growth. Based on the 0 to 20 X-ray diffraction (XRD) data, the as-grown ZnO films exhibit a preferred orientation with < 0 0 0 1 > (znO) being parallel to the < 0 0 0 1 > (sapphire). Both post-annealing and buffer-layer annealing were found to be very helpful for improving the optical properties of the ZnO films. Room temperature (RT) photoluminescence (PL) spectra of the ZnO films show strong near-band edge (NBE) emissions with completely quenched defect luminescence. The best ZnO films were achieved with a sharp neutral donor excitonic (D degrees X) emission as well as phomon replicas of free A-excitons in the 10 K PL. spectrum. (c) 2008 Elsevier B.V. All rights reserved.