Time-Resolved Photoluminescence Studies of AlInGaN Alloys

We study the two samples of AlInGaN, i.e., 1-μm GaN grown at 1030°C on the buffer and followed by a 0.6-μm-thick epilayer of AlInGaN under the low pressure of 76 Torr and the AlInGaN layer deposited directly on the buffer layer without the high-temperature GaN layer, by temperature-dependent photoluminescence (PL) spectroscopy and picosecond time-resolved photoluminescence (TRPL) spectroscopy. The TRPL signals of both the samples were fitted well as a stretched exponential decay at all temperatures, indicating significant disorder in the material. We attribute the disorder to nanoscale quantum dots or disks of high indium concentration. Temperature dependence of dispersive exponent β shows that the stretched exponential decay of the two samples comes from different mechanisms. The different depths of the localization potential account for the difference, which is illustrated by the results of temperature dependence of radiative recombination lifetime and PL peak energy.