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 GaAs 1− x Bi x . The samples used in this study were 1 µ m–1.5 µ m 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.