Heteroepitaxial growth of non‐polar ZnO films on single crystal NdGaO3 (001) substrates by MOCVD

Abstract

AbstractHigh‐quality non‐polar ZnO (11$ \bar 2 $0) films were epitaxially grown on single crystal NdGaO3 (NGO) (001) substrates. The non‐polar ZnO (11$ \bar 2 $0) films were grown by metal organic chemical vapour deposition using Zn(C5H7O2)2 and O2 gas as starting materials. X‐ray diffraction (XRD) peaks of ZnO (11$ \bar 2 $0) plane were observed in XRD patterns of 2θ‐ω scans in all films. Rotation domains were not found in XRD φ scan patterns of ZnO (11$ \bar 2 $0) films grown at a substrate temperature of 650 °C or less. XRD peaks of NGO (021) and ZnO (11$ \bar 2 $2) planes were observed at the same angle φ in the XRD φ scan patterns. The epitaxial relationship was ZnO (11$ \bar 2 $0)// NGO (001) and ZnO [0001] // NGO [010]. Lattice mismatch values along the ZnO [0001] direction and along the ZnO (1$ \bar 1 $00) direction were 5.36% and –3.70%, respectively. Growth rate was drastically decreased at the substrate temperature over 650 °C. Striped patterns along the ZnO [0001] direction were observed in atomic force microscopy images of ZnO (11$ \bar 2 $0) films grown at substrate temperatures of 600 and 650 °C. Emissions due to donor‐bound excitions were observed in photoluminescence spectra of ZnO (11$ \bar 2 $0) films measured at 10 K. It is thought that NGO (001) substrates are useful for growth of high‐quality non‐polar ZnO (11$ \bar 2 $0) films. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)