Unintentionally doped GaN with conventional single low-temperature (LT) AlN buffer layer and with double MgxNy/AlN buffer layers both were prepared. It was found that the defect density could be reduced and thus improve the crystal quality of the GaN by using double MgxNy/AlN buffer layers. GaN with double MgxNy/AlN buffer layers exhibited an asymmetrical reflection (102) and (002) with a smaller full-width at half-maximum, and a higher mobility, lower background concentration and lower etching pit density than did the GaN with the LT-AlN buffer layer.

Dislocation Reduction in GaN with Double MgxNy/AlN Buffer Layer by Metal Organic Chemical Vapor Deposition. C.W.Kuo, Y.K.Fu, C.H.Kuo, L.C.Chang, C.J.Tun, C.J.Pan, G.C.Chi: Journal of Crystal Growth, 2009, 311[2], 249-53