Correlation between atomic - scale structure and mobility anisotropy in InAs / Ga 1 2 x In x Sb superlattices

We have performed detailed characterization of atomic-scale interface structure in InAs/Ga12xInxSb superlattices using cross-sectional scanning tunneling microscopy ~STM! and established a semiquantitative correlation between interface structure and transport properties in these structures. Quantitative analysis of STM images of both ~110! and (11̄0) cross-sectional planes of the superlattice indicates that interfaces in the (11̄0) plane exhibit a higher degree of interface roughness than those in the ~110! plane and that the Ga12xInxSb-on-InAs interfaces are rougher than the InAs-on-Ga12xInxSb interfaces. The roughness data are consistent with anisotropy in interface structure arising from anisotropic island formation during growth and, in addition, a growth-sequence-dependent interface structure arising from differences in interfacial bond structure between the two interfaces. Low-temperature Hall measurements performed on these samples demonstrate the existence of a substantial lateral anisotropy in mobility that is in semiquantitative agreement with modeling of interface roughness scattering that incorporates our quantitative measurements of interface roughness using STM. @S0163-1829~98!03911-3#