Optical polarization characteristics of m-plane GaN/AlGaN quantum well structures grown on m-plane SiC substrate

Optical polarization characteristics of m-plane GaN/AlGaN QW structures grown on m-plane SiC substrate were theoretically investigated using the multiband effective-mass theory. The QW structure grown on SiC substrate shows much larger in-plane optical polarization than that grown on GaN substrate. This is attributed to the fact that the QW structure grown on SiC substrate has larger y′-polarized optical emission and smaller x′-polarized optical emission than the QW structure grown on GaN substrate. Also, the magnitude of the optical polarization is found to depend on the carrier density and decrease gradually with increasing carrier density. This can be explained by the fact that, with increasing k∥, the x′-polarized matrix element increases while the y′-polarized matrix element rapidly decreases.