The roles of island coalescence rate and strain relaxation in the development of anisotropic in-plane strains, striation features and subsequent degree of polarization in NH3 flow-rate dependent m-plane GaN were studied. In the high NH3 flow-rate samples, the results of cathodoluminescence, polarized Raman and in situ optical reflectance measurements revealed that a slower coalescence and unrelieved lattice misfit strain led to larger anisotropic in-plane strains, striated surface and luminescence patterns, and a lower density of basal-plane stacking faults and prismatic stacking faults. In contrast, a lower NH3 flow rate leads to more rapid island coalescence and fully relaxed lattice misfit strain such that relaxed in-plane strains, a reduced striation surface, and a higher density of basal-plane stacking faults and prismatic stacking faults were observed. It was suggested that the anisotropic in-plane strains, striation feature, and basal-plane stacking faults and prismatic stacking fault density were consequences of how rapidly coalescence occurs and the degree of relaxation of lattice misfit strain. In addition, the simulation results of the k•p perturbation approach confirm a larger anisotropic strain results in a smaller degree of polarization. The research results provide important information for optimized growth of non-polar III-nitrides

Surface Striation, Anisotropic In-Plane Strain, and Degree of Polarization in Nonpolar m-Plane GaN Grown on SiC. S.W.Feng, C.K.Yang, C.M.Lai, L.W.Tu, Q.Sun, J.Han: Journal of Physics D, 2011, 44[37], 375103