Effects of elastic strain on the band offset and effective mass of strained InGaSb epilayers

The effects of elastic strain induced by lattice mismatch on the effective mass and band offset at Γ point are studied in this article. We found that the effective masses (electron, light- and heavy-hole) become anisotropic in a strained layer. The theoretical calculations were made using a method of linear combination of atomic orbitals, and the overlapping integrals are adjusted in accordance with the change of atomic distance. In the k_z direction, the effective mass ratios (strain: unstrain) of the electron of In _xGa_1-xSb/GaSb structure were found to vary from 1 to 3.38 for 0≤x≤1, the corresponding ratios of the light- and heavy-hole are 1 to 3.38 and 1 to 0.99, respectively. In the k_x and k_y direction, the ratios of the light- and heavy-hole are 1 to 1.02 and 1 to 1.13, respectively. For unstrained and strained interfaces, the band offset ratios of 90:10 and 57:43 (conduction band: valence band) are obtained, respectively. Experimental studies were also performed on the In_xGa _1-xSb/GaSb strained-layer superlattice sample. It was found that the theoretical calculations agree well with experimental results in this study.