Influence of growth temperature on quaternary AlInGaN epilayers for ultraviolet emission grown by metalorganic chemical vapor deposition

A set of AlInGaN epilayers with the same alloy compositions (Al ∼ 9%, In ∼ 2%) were grown at temperatures widely ranging from 780 to 940°C by metalorganic chemical vapor deposition (MOCVD) for ultraviolet (UV) application. A clear growth mode transition from three-dimensional to two-dimensional growth with the increased temperature was observed for the first time by means of atomic force microscopy (AFM). In comparison with the low-temperature (LT) grown AlInGaN, the high-temperature (HT) grown one exhibited high crystalline quality, which was also verified by the results of X-ray diffraction (XRD) and photoluminescence (PL). Therefore, the high-temperature growth of AlInGaN is strongly recommended, particularly for UV application. Further investigation was performed on these samples by using temperature dependent PL measurements, which indicated that the poor crystalline quality of LT-grown AlInGaN was due to the improper incorporation of Al and the facile formation of nonradiative recombination centers at low growth temperatures.