- Crystal Growth of GaN by the Na Flux Method Using Na Vapor
GaN single crystals were grown by heating a Ga melt in Na vapor at 720-800℃ and 5MPa of N_2 for 8-200h. The Ga melt absorbed Na from the vapor and formed a Na-Ga melt. Transparent prismatic GaN single crystals grew spontaneously from the wall of a boron nitride crucible in the melt. The size of the prismatic GaN single crystals obtained at 800℃ was 1.0-3.0mm long and 0.3-1.0mm wide. Full-width at half maximum (FWHM) of the X-ray rocking curve measured for (10.0) reflection of prismatic crystals was 24 arcsec. Seeded growth of GaN single crystals was performed at 780℃ and N_2 pressure of 5MPa by the Na flux method with Na vapor. Transparent crystals were grown on prismatic GaN seed crystals in a Na-Ga melt with a low Na fraction, in which spontaneous nucleation of GaN was inhibited. The thickness of the crystals grown on the seeds by heating for 400 h was approximately 150μm in the directions perpendicular to the prismatic and pyramidal planes, implying the growth rate of 0.4μm/h at least.
東北大学多元物質科学研究所素材工学研究彙報 63 (1/2), 6-12, 2008-03-01