Crystal growth and characterization of thick GaN layers grown by oxide vapor transport technique

Single-crystal GaN layers of 20–40 μm thickness were grown in an oxide transport process using a mixture of commercially available Ga2O3 powder and graphite powder as precursors. Ammonia was used as the source of nitrogen in these experiments. A two-flow design was used to perform these experiments, in which, the nitrogen carrier gas was passed through the powder to transport the resulting gallium suboxide (Ga2O) towards the seed crystal. The GaN layers thus obtained from the processes were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and reciprocal space mappings. XRD patterns showed that the grown GaN layers are single crystals oriented along c-direction with wurtzite structure.