A study of transition regions in InAsPSb/InAs heterostructures grown by MOVPE

A study by secondary-ion mass spectrometry of InAs$_{x}$P$_{y}$Sb$_{1-x-y}$/InAs heterostructures ($x>$ 0.55) grown by vapor-phase epitaxy for lattice-mismatched with substrates samples revealed a noticeable and extended ($\sim$800 nm) exponential variation of the As and P content ($y$ up to 0.12) across the layer thickness. The lattice mismatch calculated from the experimentally determined distribution of the As and P components was the strongest at the interface between the epitaxial layer and the substrate and decreased away from the heterointerface into the epitaxial layer.