Single crystal growth of GaN using a Ga melt in Na vapor

GaN single crystals were grown by heating a Ga melt in Na vapor at 720-800 °C and 5 MPa of N2 for 200 h. The Ga melt absorbed Na from the vapor and formed a Na-Ga melt. Transparent prismatic GaN single crystals grew from the wall of a boron nitride crucible in the melt. Seventy five percent of Ga reacted with nitrogen and changed into GaN crystals at 720 °C when the initial amount of a Ga melt was 0.15 g. With a Ga melt of 0.75 g, 11% and 57% of Ga changed into GaN single crystals at 720 °C and at 800 °C, respectively. The rest of the Ga crystallized as a Na-Ga intermetallic compound after cooling. The size of the prismatic GaN single crystals obtained at 800 °C was 1.0-2.5 mm long and 0.3-1.0 mm wide.