Résumé:

Optical anisotropy in the growth plane has been observed by reflectance and photoluminescence (PL) spectroscopy on nitride epilayers grown on A-plane sapphire. This anisotropy results from the strongly anisotropic thermal strain which is such that the wurtzite symmetry goes from Cg, to C-2v Time-resolved PL reveals less marked anisotropy for PL decay times, due to the contributions of both radiative and non-radiative recombination channels. Nevertheless, by using a multilevel modelling of the time-dependent PL accounting for the optical anisotropy, we are able to separate the two types of recombinations. Last, we present cw and time-resolved PL results on GaN-AlGaN single quantum wells grown on A-face sapphire.