Anisotropy and growth-sequence dependence of atomic-scale interface structure in InAs/Ga1-xInxSb superlattices

We have used cross-sectional scanning tunneling microscopy to study the atomic-scale interface structure of InAs/Ga1-xInxSb superlattices grown by molecular beam epitaxy. Detailed, quantitative analysis of interface profiles obtained from constant-current images of both (110) and (1 (1) over bar 0) cross-sectional planes of the superlattice indicate that interfaces in the (1 (1) over bar 0) plane exhibit a higher degree of interface roughness than those in the (110) plane, and that the Ga1-xInxSb-on-InAs interfaces are rougher than the InAs-on-Ga1-xInxSb 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 asymmetry resulting from differences in interfacial bond structure between the superlattice layers. (C) 1997 American Institute of Physics.