Effects of strain and interface roughness between an AlN buffer layer and a ZnO film grown by using radio-frequency magnetron sputtering

ZnO thin films were grown on AlN buffer layers with different thicknesses by using radio-frequency magnetron sputtering. The effects of strain and interface roughness between the AlN buffer layers and the ZnO films were studied using synchrotron X-ray scattering experiments, scanning electron microscopy, and field emission scanning electron microscopy. As the thickness of the AlN buffer layer increased from 116 Å to 327 Å, the surface roughness of the buffer layer increased and the strain in the ZnO film on the buffer layer relaxed. The crystal quality and the surface roughness of the ZnO films were affected by the roughness of the interface and by the strain between the AlN buffer layer and the ZnO film.