Correlation between atomic-scale structure and mobility anisotropy in ${\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}}_{1-x}{\mathrm{In}}_x\mathrm{Sb}$ superlattices

We have performed detailed characterization of atomic-scale interface structure in ${\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}}_{1-x}{\mathrm{In}}_x\mathrm{Sb}$ 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 $\left(11\mathrm{}¯0\right)$ cross-sectional planes of the superlattice indicates that interfaces in the $\left(11\mathrm{}¯0\right)$ plane exhibit a higher degree of interface roughness than those in the (110) plane and that the ${\mathrm{Ga}}_{1-x}{\mathrm{In}}_x\mathrm{S}\mathrm{b}-\mathrm{o}\mathrm{n}-\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}$ interfaces are rougher than the ${\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}-\mathrm{o}\mathrm{n}-\mathrm{G}\mathrm{a}}_{1-x}{\mathrm{In}}_x\mathrm{Sb}$ 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.