Spinodal decomposition in InSb/AlAs heterostructures

The atomic structure and energy spectrum of heterostructures formed in a system of InAs/AlAs binary compounds are studied. The In$_{x}$Al$_{1-x}$Sb$_{y}$As$_{1-y}$ alloy, from which quantum wells are formed in InSb/AlAs structures, decomposes into two phases with different compositions. The characteristic dimensions of regions containing separate phases of the alloy in the structure plane are 5–7 nm. Spinodal decomposition of the alloy brings about the formation of coexisting indirect-gap regions with type-I and type-II energy spectra in quantum wells of the heterostructures.