Growth and optical properties of InxAlyGa1-x-yN quaternary alloys

InxAlyGa1-xN quaternary alloys with different In and Al compositions were grown by metalorganic chemical vapor deposition. Optical properties of these quaternary alloys were studied by picosecond time-resolved photoluminescence. It was observed that the dominant optical transition at low temperatures in InxAlyGa1-xN quaternary alloys was due to localized exciton recombination, while the localization effects in InxAlyGa1-xN quaternary alloys were combined from those of InGaN and AlGaN ternary alloys with comparable In and Al compositions. Our studies have revealed that InxAlyGa1-xN quaternary alloys with lattice matched with GaN epilayers (y approximate to4.8x) have the highest optical quality. More importantly, we can achieve not only higher emission energies but also higher emission intensity (or quantum efficiency) in InxAlyGa1-x-yN quaternary alloys than that of GaN. The quantum efficiency of InxAlyGa1-xN quaternary alloys was also enhanced significantly over AlGaN alloys with a comparable Al content. These results strongly suggested that InxAlyGa1-x-yN quaternary alloys open an avenue for the fabrication of many optoelectronic devices such as high efficient light emitters and detectors, particularly in the ultraviolet region. (C) 2001 American Institute of Physics.