Growth of a Large GaN Single Crystal Using the Liquid Phase Epitaxy (LPE) Technique

We grew a 12×5×0.8 mm GaN single crystal using the liquid phase epitaxy (LPE) method with Na flux. This GaN single crystal was grown on a 3 µm-thick GaN thin film synthesized on sapphire using the metal organic chemical vapor deposition (MOCVD) method. It grew in a polyhedral form larger than the MOCVD-GaN substrate. Results indicate that a MOCVD-GaN thin film on a sapphire substrate functions as a seed crystal in Na flux. The use of mixed nitrogen gas containing 40% ammonia instead of pure N2 gas also enabled the growth of a 10 µm-thick GaN homo-epitaxial film on an MOCVD-GaN film under 5 atm, the lowest reported pressure for growing GaN in Na flux. In this paper, we describe the liquid phase epitaxy (LPE) technique for growing bulk GaN single crystals, as well as the results of photoluminescence (PL) measurements. We also compare the PL intensity of the bulk GaN obtained in this study and the MOCVD-GaN. PL measurements revealed that the peak intensity of GaN single crystal grown by LPE indicates 40 times larger than MOCVD-GaN film. Also, dislocation density of bulk GaN crystals could be drastically reduced by the LPE growth technique.