MOVPE growth and properties of non-polar InGaN/GaN multiple quantum wells on γ-LiAlO₂ substrates

We report on growth as well as structural and optical properties of m-plane InGaN/GaN multiple quantum wells (MQWs) grown on LiAlO₂ substrate by metal-organic vapor phase epitaxy. During the growth, surface nitridations of LiAlO₂ substrate and Mg-doped InGaN buffer layers were employed. Pure m-plane and two-orientation (mixture of c- and m-plane) samples were prepared and verified by X-ray diffraction and Raman scattering. Atomic force microscopy (AFM) image of our m-plane surface morphology reveals a "fabric"-like pattern, i.e., stripes running perpendicular to each other. Photoluminescence from the m-plane MQW has polarization anisotropy, which can be attributed to the anisotropic in-plane strain. In two-orientation sample, we found that this optical polarization property survives; yet it is weakened. This indicates that polarized emission is a robust optical property in our samples. Therefore InGaN/GaN MQWs on LiAlO₂ have potential for application in efficient polarized light emitters.