Temperature dependence of the band gap of GaSb1−xBix alloys with 0 < x ≤ 0.042 determined by photoreflectance

Abstract

GaSb1−xBix layers with 0 < x ≤ 0.042 have been studied by photoreflectance in 15–290 K temperature range. We found that due to the incorporation of Bi atoms into the GaSb host, the E0 band gap-related transition redshifts (∼30 meV per 1% Bi) and significantly broadens. The shift of the E0 transition in the temperature range 10–270 K has been found to be ∼70 meV, very similar to the energy shift in GaSb over the same temperature range. We analyzed the energy and broadening of the E0 transition using the Varshni and Bose-Einstein formulas and found that the Varshni and Bose-Einstein parameters of GaSb1−xBix are similar to those of GaSb. Moreover we concluded that the inhomogeneities in GaSb1−xBix alloys is less important than in dilute bismide arsenides since Bi atoms are more similar to Sb atoms (in electronegativities and ionic sizes).