Electronic properties of metamorphic GaSbBi films on GaAs

We report on the electronic, structural, and optical properties of epitaxial GaSbBi films with varying Bi-concentration (up to 7%Bi) grown on semi-insulating GaAs(100) substrates. The 1 μm thick GaSbBi epilayers exhibit fully relaxed narrow x-ray diffraction peaks and smooth surface morphology comparable to that of high-quality GaSb epilayers on GaAs. Low temperature photoluminescence spectra exhibit bandgap shrinkage consistent with Bi alloying. Electrical Hall measurements indicate a reduction in hole concentration and no change in the hole mobilities with increasing Bi content for the nominally undoped GaSbBi alloy. The residual hole concentration reduces from the 10¹⁸ cm⁻³ level for a reference GaSb sample to the low 10¹⁷ cm⁻³ level with increasing Bi content. Hole mobility values of around 300 cm²/Vs are observed independent of the Bi content. These dependencies are attributed to the Bi surfactant effect and Bi-induced defect formation.