Effect of additives on liquid phase epitaxy growth of non-polar GaN single crystals using Na flux method

Non-polar GaN substrates have attracted attention because they can improve the performance of GaN devices. Growth of high-quality non-polar GaN single crystals, however, has not been realized. Here, we attempted to grow m-plane GaN crystals using the Na flux method and investigated the effect of additives such as Ca and Li in Na flux on transparency, surface roughness, and crystallinity. We found that the addition of Ca and Li improved the transparency and the surface roughness of the crystals. Moreover, high-temperature growth improved crystallinity and decreased impurities such as Ca, Li, and O in GaN crystals. We also found that the crystallinity did not depend on the concentrations of impurities in GaN crystals. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)