ELECTRON-TRANSPORT IN INAS/GA(1-X)IN(X)SB SUPERLATTICES

We have experimentally investigated the electron transport properties of a series of n-type InAs/Ga1-xInxSb superlattices with InAs thicknesses (d1) between 25 and 86 angstrom and a fixed Ga1-xInxSb thickness (d2) of 25 angstrom. Interface roughness scattering is found to dominate the electron mobility (mu(n)), but with a much weaker dependence on layer thickness than the conventional d1(6). We observe an abrupt decrease in mu(n)(d1) at the semiconductor-to-semimetal transition point and the coexistence of two electron species in semimetallic samples. All of these findings can be understood by considering the theoretical band structures for InAs/Ga1-xInxSb superlattices with thin d2, which differ considerably from those in InAs/GaSb structures with comparable energy gaps and thick d2, but are strikingly similar to results for HgTe/CdTe. Since the system is strongly 3D rather than 2D in character, it is surprising that in some samples the quantum oscillations in the Hall conductivity are much larger than those in the diagonal conductivity.