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Photoreflectance and photoluminescence study of annealing effects on GaAsBi layers grown by metalorganic vapor phase epitaxy

The optical properties of GaAsBi layers grown by atmospheric pressure metalorganic vapor phase epitaxy on p-type GaAs substrates and annealed at different temperatures are investigated by photoreflectance and photoluminescence spectroscopies. Photoreflectance spectra show no significant shift in the band gap energy of GaAs0.965Bi0.035 with annealing temperature except 600 °C for which the band gap energy reaches a minimum value corresponding to a red shift of 60 meV. The low temperature photoluminescence spectra of GaAsBi layers show a broad band centered at ∼1.36 eV. The temperature dependence of the 1.36 eV emission band in addition to the increasing intensity of this band with bismuth flow suggests that it is originated from Bi clusters or from complex defects probably located at the surface/interface of the GaAsBi epilayer.