Theory of optical properties of segregated InAs/GaSb superlattices

The authors study the effects of interfacial atomic segregation on the electronic and optical properties of InAs/GaSb superlattices. They describe their atomistic empirical pseudopotential method and test its performance against the available experimental data. They show its ability to predict the band structure dependence on the detailed atomic configuration, and thus to properly account for the effects of interfacial atomic segregation and structural disorder. They also show how their method avoids the approximations underlying the pseudopotential method of Dente and Tilton, which gives different results. The application of the proposed method to the InAs/GaSb superlattices allows the explanation of some observed experimental results, such as: the bandgap difference between (InAs)₈/(GaSb)₈ superlattices with almost pure InSb-like or GaAs-like interfaces; the large blue shift of the bandgap when the growth temperature of the superlattice increases; and the blue shift of the bandgap of (InAs)₈/(GaSb)_n superlattices with increasing GaSb period n. They present a detailed comparison of their predicted blue shift with that obtained by other theories.