Epitaxial Growth of Nonpolar ZnO Films on Sapphire Substrates with a Terrace-Step Nanorelief

Abstract

The processes of fabrication of nonpolar (11\(\bar {2}\)0) ZnO films with a thickness of up to 7.25 µm on (1\(\bar {1}\)02) sapphire (Al₂O₃) substrates with a terrace-step surface nanostructure by magnetron sputtering at a growth rate of up to 4.5 nm/s has been studied. The effect of steps in the initial growth stages has been found, which leads to the formation of isolated ZnO nanostructures decorating the steps. In all next growth stages, a continuous (11\(\bar {2}\)0) epitaxial ZnO film with the longitudinal [0001] axis of crystallites, oriented parallel to the step edge on the sapphire surface has been observed. It is established that the interplanar spacing in the ZnO films in the [11\(\bar {2}\)0] direction, determined from the X-ray diffraction data, depends on the thickness and deposition rate and approaches the value of X-ray diffraction references for ZnO with an increase in thickness to 7.25 µm and a decrease in the growth rate to 2.1–2.3 nm/s.