Photoluminescence from localized states in GaAsBi epilayers

The structural and optical properties of GaAs
_1-x
Bi
_x
samples with x = 0.048 and 0.06 were investigated by high resolution X-ray diffraction (HR-XRD) and photoluminescence (PL). The HR-XRD results show that both samples have a smooth and coherent GaAs
_1-x
Bi
_x
/GaAs interface. The PL peak energy shows an S-shape behavior with temperature (10 K to room temperature) which is an evidence of carrier localizations. An Arrhenius analysis reveals that the thermal quenching activation energy is 30 and 19 meV for the GaAs
_0.952
Bi
_0.048
and GaAs
_0.94
Bi
_0.06
sample, respectively. It was found that the activation energy is not necessarily originated from alloy fluctuations but may also due to CuPt ordering-induced band gap fluctuations. The power dependent PL indicates that the localized energy states are continuously present and located up to 40-47 meV from the valence band.