Effects of nitrogen incorporation and thermal annealing on the optical and spin properties of GaPN dilute nitride alloys

Abstract : Here, we report on the structural, optical and magneto-optical properties of as-grown and thermal annealed GaPN thin films containing different N concentrations grown by Solid-Source Molecular Beam Epitaxy on GaP substrates. A wide range of characterization techniques were used to investigate the effect of N incorporation and thermal annealing effect of GaPN/GaP epilayers for a N content between 0.5% and 3%. Our results have shown that as we increase the N content the PL peak energy presents a red shift which is explained by a band gap reduction. However, important effects of exciton localization on optical properties were also evidenced from cw and time resolved PL (PLRT) and magneto-PL. Our results have demonstrated that as the concentration of N is increased, exciton localization effect is enhanced. A substantial improvement of the optical quality and spin properties of the epilayers has been observed after thermal annealing which are significantly more important for samples with higher nitrogen contents.