Effect of anion-to-cation supplying ratio on the surface morphology of AlN films grown on ZnO substrates at low temperature

The authors investigated the evolution of surface morphology of AlN films grown on ZnO substrates at low temperature (LT) (400 degrees C) as a function of anion/cation supplying ratio (V/III ratio). Unlike the well-known favorable growth conditions for high-temperature growth, smooth-surface LT-AlN layers were obtained under the O-polar surface, stoichiometric, and N-rich conditions. LT-AlN layers revealed smooth surface (roughness in root mean square=0.20 nm for AlN on O-polar ZnO and 0.44 nm for AlN on Zn-polar ZnO) and quite low etch-pit density (similar to 2 x 10(6) cm(-2) for AlN/Zn-polar ZnO). (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3264479]