Terahertz excitation spectra of GaAsBi alloys

Terahertz excitation spectroscopy was used for the determination of energy separation between the main (Γ) and subsidiary (L and X) conduction band valleys of GaAs1−xBix. The samples used in this study were 1 µm-1.5 µm thick bismide layers grown by Molecular Beam Epitaxy on GaAs substrates. They contained up to 8% of bismuth as determined by high resolution x-ray diffraction (HR-XRD) and reciprocal space mapping (RSM), taking into account the layer relaxation. It was found that both subsidiary conduction band valleys at L and X points of the Brillouin zone move away from the conduction band minimum at rates of 18 meV/%Bi and 25 meV/%Bi, respectively, with increasing Bi content in the alloy.