Structural characterization of GaN single crystal layers grown by vapor transport from a gallium oxide (Ga₂O₃) powder source

The sublimation growth technique is highly attractive as a commercially viable GaN substrate technology on account of its simplicity and relatively high growth rates. Sublimation growth of GaN using GaN powder source, however, is hampered by formation of liquid Ga in the source. To overcome this limitation, an oxide transport process using a mixture of gallium oxide (Ga ₂O₃) powder and graphite powder as precursors with nitrogen gas as carrier and ammonia as the source of nitrogen has been developed. GaN layers grown by this process were studied by optical microscopy, synchrotron white beam x-ray topography (SWBXT) and high resolution x-ray diffraction (HRXRD) to characterize their structural properties. Studies reveal that the GaN layers grown are single crystal but characterized by dislocation densities and impurities higher than those obtained using GaN powder source. Observed defect distribution is correlated with growth conditions to deduce optimal growth procedure.