Growth mode in strained ZnO films on Al2O3(0001) during sputtering

Abstract

We investigated the temperature dependence of growth mode in highly mismatched sputter-grown ZnO/Al2O3(0001) heteroepitaxial films using real-time synchrotron X-ray scattering. We find that the growth mode changes from 2 dimensional (2D) layer to 3D island in early growth stage with temperature (300 degrees C - 500 degrees C). At around 400 degrees C, however, intermediate 2D platelets nucleate in early stage, act as nucleation cores of 3D islands and transform to misaligned state during further growth. The results of the strain evolution during growth suggest that the surface diffusion is a major factor in determining the growth mode in the strained ZnO/Al2O3( 0001) heteroepitaxy.