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.