Band alignments and offsets in In(As,Sb)/InAs superlattices

The band alignments and band offsets were investigated for In(As,Sb)/InAs superlattices of various periods and compositions. Magnetoabsorption experiments allowed identification of subband energies and in-plane reduced masses. Using an 8 x 8 k . p band-structure calculation which takes account of nonparabolicity, valence subband mixing, and strain effects, we are able to fit calculated absorption curves to transition energies and reduced masses. Comparison of fits on several samples confirm that the electrons lie in the In(As,Sb) layer and the holes in the InAs layer. By using the fitted curve offsets, we are able to calculate the fractional conduction-band-offset parameter, Q(c), which for a type-II heterostructure can be greater than 1 and which we found to be 2.06 +/- 0.11.