The Effects of Ba-Additive on Growth ofa-Plane GaN Single Crystals Using Na Flux Method

Large-area nonpolar GaN substrates with high crystallinity are necessary to improve the performance of GaN devices. Nonpolar GaN substrates of 2-in. diameter have been commercially fabricated by growing along the nonpolar direction on heterogeneous substrates. However, the crystallinity of the nonpolar GaN substrates requires improvement. Here, we grew a -plane GaN crystals using the Na flux method and investigated the effects of a Ba-additive on surface morphology and crystallinity. We found that the crystallinity of the crystals grown by the Na flux method was greatly improved compared with that of seed substrates. Moreover, the use of the Ba-additive suppressed the formation of voids that occurred during the Na flux growth without the Ba-additive. As a result, a -plane GaN crystals with high crystallinity were produced using the Na flux method with the Ba-additive.