Growth and photoluminescence of InAlGaN films

Two quaternary InAlGaN films were grown by metal-organic chemical-vapor deposition (MOCVD) on sapphire (0001) substrates with and without high-temperature GaN interlayer, respectively.Therespectively. The structural and optical properties of the quaternary films were investigated by high-resolution X-ray diffraction (HRXRD), high-resolution electron microscopy (HREM), temperature-dependent photoluminescence (PL) spectroscopy and time-resolved photoluminescence (TRPL) spectroscopy. According to the the HRXRD and PL results, it is demonstrated that two samples have the same crystal quality. The TRPL signals of both samples were fitted well as a stretched exponential decay from 14 K to 250 K, indicating significant disorder in the materials, which is attributed to recombination of excitons localized in disorder quantum nanostructures such as quantum dots or quantum disks originating from indium (In) clusters or In composition fluctuation. The cross-section high-resolution electron microscopyHREM measurement further confirmed proves that there exist disorder quantum nanostructures in the quaternaryquantum dots or disks of high indium concentration. By investigating the T temperature dependence of the dispersive exponent β, it is showsn that the stretched exponential decays of the two samples comes originate from different mechanisms. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)