Temperature dependence of GaAs1-xBix band gap studied by photoreflectance spectroscopy

We performed photoreflectance (PR) spectroscopy in order to investigate the fundamental band gap of GaAs1-xBix alloys. The temperature dependence of the band gap energy was evaluated by analyzing of the Franz-Keldysh oscillation in the PR spectra. With increasing Bi content, the band gap energy of GaAs1-xBix alloy is reduced, which shows a large optical bowing. The temperature coefficient of the band,gap decreases appreciably in alloys with increasing Bi content. For x = 0.026, the temperature coefficient near room temperature is -0.15 meV/K which is 1/3 of the value for GaAs.