Bulk GaN single crystals: a reinvestigation of growth mechanism using Li3N flux

The GaN growth mechanism using Li₃N flux was reinvestigated by designing a new experiment that allowed us to grow GaN simultaneously under varying Ga/Li₃N molar ratios. The results confirm the two-step reactions involved in the Ga–Li₃N system: Li₃N+Ga→Li₃GaN₂+Li (1) and Li₃GaN₂+Ga→GaN+Li (2). It is found that reaction (2) is the main cause leading to small GaN crystals in the products. Larger GaN crystals, however, can grow by a different pathway. The growing process is concerned with the formation of Li–Ga–N melt by dissolving Li₃GaN₂ in Li–Ga melt after reaction (1). GaN crystals up to 3 mm grow from the Li–Ga–N melt upon cooling on the GaN particles by reaction (2). Our results suggest that it is necessary to restrain reaction (2) by choosing proper Ga/Li₃N molar ratios so as to obtain GaN crystals in larger size. PACS 81.05.Ea; 81.10.Dn