Growth temperature dependence of structural properties of AlN films on ZnO (0001¯) substrates

The authors have investigated substrate temperature dependence of the structural properties of AlN grown on atomically flat ZnO (0001¯) substrates using pulsed laser deposition. The growth of AlN on ZnO at above 500°C proceeds in a three-dimensional mode and results in the formation of films with poor crystallinity and rough surfaces. However, reduction in the growth temperature leads to a remarkable improvement in crystalline quality and surface morphology. The authors have found that AlN films with stepped and terraced surfaces grow in the layer-by-layer mode at substrate temperatures below 300°C. X-ray reflectivity measurements have revealed that these improvements in structural properties can be attributed to the suppression of the interfacial reactions between AlN and ZnO.