Vapor-phase epitaxy of high-crystallinity GaN films using Ga2O vapor and NH3

In this study, vapor-phase epitaxy (VPE) of GaN oriented-film was performed using Ga2O vapor as the Ga source. Ga2O vapor was obtained by reducing Ga2O3 powder with H2 gas at 1000 °C. The Ga2O vapor was then reacted with NH3 on a seed substrate at 1100–1150 °C. A high quality GaN substrate (1 mm thick, with full widths at half maximum of GaN (0 0 0 2) X-ray rocking curve of 107–110 arcsec) prepared by the Na-flux method were used as the seed substrate. After 30 min of growth, a 3-μm flat GaN (0 0 0 1) epitaxial layer was grown on the seed substrate. X-ray diffraction (XRD) measurements showed that the FWHM of the GaN epitaxial layer was 74–111 arcsec, showing high crystallinity. Secondary ion mass spectrometry (SIMS) analysis showed that the oxygen concentration in the epitaxial layer was 1.5×1018 atoms/cm3. Although an oxide was used as the raw material, oxygen concentration close to those in GaN crystal grown by the hydride vapor phase epitaxy (HVPE) and metalorganic vapor phase epitaxy (MOVPE) were achieved. We concluded that the VPE method using Ga2O vapor has potential as a simple vapor-phase-growing technique for high-quality GaN films.