Thermal annealing effects on the optical and structural properties of (1 0 0) GaAs1−xBix layers grown by Molecular Beam Epitaxy

The effects of long time thermal annealing at 200 °C on the optical and structural properties of GaAs1−xBix alloys were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). FESEM images show that bismuth islands nucleate on the surface and their diameter increases after annealing. It was observed a PL intensity enhancement and a small blue shift in PL peak energy after thermal annealing at 200 °C for 3 h of GaAs1−xBix alloys which was associated to the reduction of the density of defects. However these defects are not completed removed by thermal annealing although an important PL intensity improvement is observed.