Growth of Large GaN Single Crystals on High-Quality GaN Seed by Carbon-Added Na Flux Method

Seeded growth on high-quality GaN seed was studied using a carbon-added Na flux method. A GaN single crystal (8.6 mm long, 5 mm high) was grown in 96 h without polycrystal formation on a crucible. Under a carbon-added condition, dependence of the growth rate of the seed and the growth habit on the flux composition was studied. We found that the growth rate was higher with Ga-poor flux, resulting in a high growth rate of 30 µm/h along the c-axis and 33 µm/h along the a-axis (66 µm/h for both sides). The growth habit changed from prismatic to pyramidal with increasing Ga composition.