Abstract
We have investigated the effect of long thermal annealing (3 h) at 200 °C on the physical properties of GaBiAs layers with a Bi concentration of 3% by using photoluminescence (PL) and polarized resolved PL under magnetic fields up to 14 T. The PL intensity and the diamagnetic shift of the annealed samples increased substantially. This indicates a reduction of carrier/exciton localization due to defects. In addition, it was found that the degree of the electron spin polarization increases up 41% at 14 T after thermal annealing due to the reduction of the density of defects.