Characterization of a ZnO Epilayer Grown on Sapphire by using Rutherford Backscattering/Channeling and X-Ray Diffraction

A ZnO layer with rather good crystalline quality (χ_min=9.4%) is grown on a sapphire substrate by plasma enhanced chemical vapor deposition (PECVD). Rutherford backscattering (RBS)/channeling and high-resolution x-ray diffraction (XRD) are used to characterize the elastic strain in the ZnO epilayer. The tetragonal distortion is positive and depth dependent. It is highest near the interface and decreases towards the sample surface. By combining the results of RBS and XRD, the average elastic strains in the parallel and the perpendicular directions can be calculated to be 0.50% and −0.17%, respectively.