Effects of substrate on the structure and orientation of ZnO thin film grown by rf-magnetron sputtering

Abstract

X-ray diffractions, Nomarski microscopy, scanning electron microscopy, and photoluminescence have been used to study the effects of substrate on the structure and orientation of ZnO thin films grown by rf-magnetron sputtering. GaAs(001), GaAs(111), Al2 O3 (0002) (c -plane), and Al2 O3 (1 1- 02) (r -plane) wafers have been selected as substrates in this study. X-ray diffractions reveal that the ZnO film grown on GaAs(001) substrate is purely textured with a high c -axis orientation while that grown on GaAs(111) substrate is a single ZnO(0002) crystal; a polycrystalline structure with a large-single-crystal area of ZnO(0002) is obtained on a c -plane Al2 O3 substrate while a ZnO (11 2- 0) single crystal is formed on an r -plane Al2 O3 substrate. There is absence of significant difference between the photoluminescence spectra collected from ZnOGaAs (001), ZnOGaAs (111), and ZnO Al2 O3 (0002), while the photoluminescence from ZnO Al2 O3 (1 1- 02) shows a reduced intensity together with an increased linewidth, which is, likely, due to the increased incorporation of native defects during the growth of ZnO (11 2- 0). © 2007 American Institute of Physics.