Quantitative study of the interfacial intermixing and segregation effects across the wetting layer of Ga(As,Sb)-capped InAs quantum dots

Quantitative chemical information from semiconductor nanostructures is of primary importance, in particular at interfaces. Using a combination of analytical transmission electron microscopy techniques, we are able to quantify the interfacial intermixing and surface segregation across the intricate non-common-atom wetting layer (WL) of Ga(As,Sb)-capped InAs quantum dots. We find: (i) the WL-on-GaAs(buffer) interface is abrupt and perfectly defined by sigmoidal functions, in analogy with two-dimensional epitaxial layers, suggesting that the interface formation process is similar in both cases; (ii) indium segregation is the prevailing mechanism (e.g., over antimony segregation), which eventually determines the composition profile across the GaAs(cap)-on-WL interface