Effect of defects on strain state in nonpolar a-plane GaN

A1. Defects A1. High resolution X-ray diffraction B1. Nitrides B2. Semiconducting III-V materials abstract We have investigated the influence of basal stacking fault (BSF) and impurity related defect on the strain state of a-plane GaN epilayers. Four a-plane GaN epilayers were grown on r-plane sapphire using different growth strategies by metalorganic chemical vapor deposition. It is found that with a growing number of stacking fault, both the anisotropic in-plane strain and compressive out-plane strain along c-axis are relieved. Epitaxial lateral overgrowth with a TiN interlayer is an effective way to relieve in- plane strain and reduce BSF density. The extrapolated lattice parameters free of biaxial strain increase with the normalized yellow luminescence intensity. Hydrostatic strain induced by impurity-related defects is the possible cause of this phenomenon.