Epitaxial growth and optical characterization of AlInGaN quaternary alloys with high Al/In mole ratio

Abstract

AlInGaN quaternary epitaxial layers with high Al/In mole ratio were grown on GaN/sapphire templates by metalorganic chemical vapor deposition (MOCVD). The optical and structural properties were characterized by various kinds of technical tools. The full width at half-maximum of the (0002) X-ray diffraction rocking curves was found to decrease as the Al/In mole ratio was increased. The density and size of V-shaped defect pits observed on the surface of AlInGaN epitaxial layers with energy-dispersive X-ray spectroscopy could be reduced by lowering the MOCVD growth pressure. It was also discovered with the variable temperature photoluminescence spectra that the emission peak energy for the AlInGaN epitaxial layers demonstrated an S-shaped shift (red shift–blue shift–red shift) behavior with increasing the measurement temperature. This feature was more significant for those AlInGaN epitaxial layers with lower Al/In mole ratio.