Electrical transport in InAs/GaSb superlattice: role of surface states and interface roughness

Abstract

We have modeled electrical properties of InAs/GaSb superlattice (SL) using band structure calculations based on an atomistic empirical pseudopotential method and mobility estimates. The model quantitatively explains the experimental results obtained on a SL sample using the technique of ‘quantitative mobility spectrum analysis (QMSA)’. We show that the factors that influence in-plane electrical transport in this system are different under low- and high-temperature regimes. This difference primarily arises from the location of conducting regions. At lower temperatures the electron density, emanating from the defects in a cap GaSb layer, is essentially confined to a few wells near the surface of the SL. At higher temperatures, conduction is dominated by thermally excited carriers which are more uniformly spread over the entire SL. We identify dominant scattering mechanisms that limit the electron mobility under both regimes and show that interface roughness plays a significant role in the high-temperature regime.