Luminescence morphology and x-ray diffraction features of InGaN materials grown on sapphire by metalorganic chemical vapor deposition

摘要

Abstract: InGaN thin films were grown by low-pressuremetalorganic chemical vapor deposition andcharacterized by photoluminescence with variableexcitation intensity and temperature, room-temperaturecathodoluminescence (CL), high resolution X-raydiffraction, scanning-electron-microscopy (SEM) andatomic force microscopy (AFM). For PL, all the sampleshow dominant peaks at around 2.9 eV and extra peaks orshoulders at 2.8 eV at 6K. We concluded that the lowenergy peak is due to the localized near-band edgetransition from the phase-separated InGaN mesoscopicstructure with high In-content. The strong luminescenceof the low of nanostructure or quantum dots. AFM imagesshowed that phase-separated InGaN samples have invertedhexagonal pits which are formed by the In segregationon the surfaces. Room temperatures cathodoluminescenceand imags at wavelengths corresponding to the GaN bandedge, the In-poor and In rich regions were studied. Itwas shown that phase separated In-rich regions formedat the periphery of the hexagonal pits. !18