In situ X-ray diffraction monitoring during metalorganic vapor phase epitaxy growth of low-temperature-GaN buffer layer

We investigated in situ X-ray diffraction (XRD) monitoring during the growth of low-temperature (LT)-GaN buffer layers on the (0001) c-plane sapphire substrates. The in situ XRD monitoring made it possible to observe the crystalline structures during their growth. We investigated the temperature dependence of LT-GaN buffer layers by in situ XRD monitoring during the thermal annealing of the LT-GaN layers. We clearly observed the evolution process, in which an LT-GaN buffer layer grown at 535 °C was crystallized into a hexagonal structure by thermal annealing at temperatures of up to 1090 °C. We also found that the LT-GaN buffer layer was transformed into nano size hexagonal single-crystal islands upon annealing by atomic force microscopy. The crystalline quality of the subsequent GaN layer strongly depended on the growth temperature of the LT-GaN buffer layer. © 2012 Elsevier B.V.