Three-Dimensional Visualization Of Sb Segregation In Inas/Inassb Superlattices Using Atom Probe Tomography

The Sb concentration profile in an nBn photodetector containing an InAs/InAsSb type-II superlattice is collected and analyzed using atom probe tomography. A 3D reconstruction comprises the full composition of 31 periods. The Sb concentration profile is evaluated for the entire 31 period stack, as well as each individual period using segregation models from Muraki and Wood. Trends in the asymmetric Sb profile show a consistent non-negligible Sb concentration in the InAs layers and a lower Sb concentration in the InAsSb with respect to the target concentration.