Effect of structural defects on InSb/AlxIn1−x Sb quantum wells grown on GaAs (0 0 1) substrates

We investigate oriented abrupt steps (OASs), a type of surface defect in InSb/AlxIn1−xSb quantum-well (QW) samples grown on GaAs (001) substrates. Previous atomic force microscopy studies have reported that the OASs are oriented along the [110] and View the MathML source directions and have an inclination angle of ∼5°–15° with respect to the sample surface. Our plan-view and cross-sectional transmission electron microscopy analyses reveal that the OASs are the terminal edges of threading micro-twins at the sample surface. Hall effect measurements indicate that the density of OASs correlates with the electron mobility in the InSb QWs.