In-Plane Optical Anisotropy in InxGa1—xN/GaN Multiple Quantum Wells

We have investigated the crystal orientation dependence of optical properties in InxGa1—xN/GaN multiple quantum wells. The spectral peak and intensity of the micro-photoluminescence emission for different crystal orientations were found to have sixfold symmetry. Quite interestingly, the refractive index obtained from the interference pattern, also varies with the crystal orientation. The 60 degree periodic anisotropy of electronic transitions as well as optical parameters were interpreted in terms of the formation of hexagonal truncated pyramidal In-rich clusters. Our result provides an alternative solution to improve the designs of photonic and electronic devices based on nitride semiconductors.