Surface and subsurface imaging of indium in InGaAs by scanning tunneling microscopy

Investigating the ternary InxGa1−xAs alloy (x ∼ 12%) by cross-sectional scanning tunneling microscopy, we find that on the UHV-cleaved (110) surface the In distribution in both the surface and the first subsurface layer can be atomically resolved in the empty- and filled-state images, respectively. This is found to be mostly a geometric effect due to the larger size of the In. We apply this method to study the incorporation of In during the growth of In0.12Ga0.88As quantum wires on nonplanar substrates. Strong In segregation in the growth direction is seen in the structure, and we compare the incorporation profiles across the quantum wire and a planar quantum well. No In clustering beyond the statistical expectation is observed.