Calculation of InAs/AlSb(001) band offsets: Effect of strain and interfacial atomic structure

The band offsets of strained InAs grown on an AlSb(001) substrate are calculated for both the In-Sb and Al-As interfaces. A valence band offset of 0.19 eV (AlSb valence max higher) is calculated within first-principles local density functional theory, independent of the type of interfacial bonding. Short-period superlattices with identical InAs and AlSb lengths but differing only in the type of interfacial bond exhibit, however, quantum-confined states that can differ by 0.25 eV, and this is explained in terms of the superlattice wave functions. The 0.13 eV strain-induced decrease in the InAs gap leads to an extremely small energy difference of 0.04–0.10 eV between the InAs conduction minimum and the AlSb valence maximum, and presents a possible explanation for the increase in the InAs quantum well charge seen with increasing temperature.