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 Ga₂O ₃ 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.