Excitonic recombination dynamics in non-polar and semi-polar AlGaN/GaN multiple QWs

We compare the optical properties of GaN/Al0.15Ga0.85N multiple quantum wells grown on an m-plane (10-10) oriented GaN substrate with those of (1-101)-oriented GaN/Al0.15Ga0.85N multiple quantum wells grown by metal-organic chemical vapor deposition on a patterned (001) 7°-off oriented silicon substrate. The optical properties are studied in 8K-300K temperature range. They reveal strong in-plane optical anisotropies as predicted by group theory. Polarized time resolved temperature- dependent photoluminescence experiments are performed providing access to the relative contributions of the non-radiative and radiative recombination processes. We deduce the variation of the radiative decay time with temperature in the two polarizations. A global comparison of the light emission efficiency in both samples is finally addressed and brought in agreement with the predictions of k.p calculations.