Growth and photoluminescence studies of AlN thin films with different orientation degrees

AlN thin films with different orientation degrees, i.e., (0002) textured, (0002) textured with traces of non-(0002) components, and randomly oriented, were deposited by radio frequency magnetron sputtering. The films were comprehensively characterized using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The dependence of orientation degree on the nitrogen partial pressure during the deposition processes was revealed. Based on microstructural analysis with high-resolution transmission electron microscopy and photoluminescence measurements, the correlation between the orientation degree and photoluminescence was investigated. It was suggested that the defects induced in large-angle grain boundaries were possibly responsible for the enhanced non-band-edge emission.