The effect of the thermal annealing on the optical and spin properties in GaAs0.44Sb0.56 epilayers grown on InP was investigated via photoreflectance, power-dependent and time-resolved photoluminescence spectroscopy as well as optical orientation measurement. The carrier’s localization and the optical spin detection efficiency increase with an increase of annealing temperature up to 600 °C. The enhancement of the spin detection efficiency is attributed to both the shortening of the electron lifetime and the prolonging of the spin lifetime as a result of the enhanced carriers’ localization induced by the annealing process. Our results provided an approach to enhance spin detection efficiency of GaAsSb with its PL emission in the 1.55 μm region.

High‐quality lattice‐matched and mismatched GaAs1–xSbx (0.37 < x < 0.57) epilayers are grown on InP by molecular beam epitaxy. The localized states are confirmed by the S‐shape behavior of the temperature‐dependent photoluminescence (PL). With the help of a model based on a redistribution process of localized excitons, the degree of carrier localization is estimated quantitatively. It is found that the degree of carrier localization reaches a maximum for the lattice‐matched sample with Sb = 47.7%, indicating that carrier localization effects are mainly due to compositional fluctuations. This result is corroborated by the power‐dependent PL. In addition, power‐dependent Raman measurements give a hint that the thermal conductivity of the lattice‐matched sample is ≈50% higher than that of lattice‐mismatched samples with Sb = 37.9% and 56.2%. Thus the abnormal S‐shape behavior (blue–redshift) that occurs in the power‐dependent PL from the lattice‐mismatched GaAsSb samples is attributed to both the lower degree of carrier localization and the enhanced laser heating effect caused by their smaller thermal conductivity.

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