Piezoreflectance and photoreflectance study of annealing effects on GaAs0.916Sb0.084 and GaAs0.906Sb0.075N0.019 films on GaAs grown by gas-source molecular beam epitaxy

Thermal annealing effects of GaAs 0.916 Sb 0.084 and GaAs 0.906 Sb 0.075 N 0.019 films grown on GaAs substrates by gas-source molecular beam epitaxy have been characterized by piezoreflectance (PzR) and photoreflectance (PR). By a comparison of relative intensity of PzR and PR spectra, the identification of conduction to heavy-hole (HH) band and conduction to light-hole (LH) band transitions originated from the strained induced valence band splitting have been achieved. The near band edge transition energies are blue-shifted, and the splitting of HH and LH bands is reduced after thermal annealing treatment. The annealing effects of GaAs 0.906 Sb 0.075 N 0.019 are found to be more pronounced than that of GaAs 0.916 Sb 0.084 . The temperature dependences of near band edge transition energies are analyzed using Varshni and Bose―Einstein expressions in the temperature range from 15 K to 300 K. The parameters that describe the temperature variations of the near band edge transition energies are evaluated and discussed.