Effects of interfacial atomic segregation on optical properties of InAs/GaSb superlattices

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Abstract
Largely because of the lack of detailed microscopic information on the interfacial morphology, most electronic structure calculations on superlattices and quantum wells assume abrupt interfaces. Cross-sectional scanning tunneling microscopy (STM) measurements have now resolved atomic features of segregated interfaces. We fit a layer-by-layer growth model to the observed STM profiles, extracting surface-to-subsurface atomic exchange energies. These are then used to obtain a detailed simulated model of segregated InAs/GaSb superlattices with atomic resolution. Applying pseudopotential calculations to such structures reveals remarkable electronic consequences of segregation, including a blueshift of interband transitions, lowering of polarization anisotropy, and reduction of the amplitude of heavy-hole wave functions at the inverted interface.