Resonant Raman scattering and spectral ellipsometry on InAs/GaSb superlattices with different interfaces

We have used Raman spectroscopy and spectral ellipsometry to investigate InAs/GaSb short-period superlattices (SLs), grown by molecular-beam epitaxy, with either InSb- or GaAs-like interfaces. Room-temperature ellisometric measurements show spectral features in the dielectric function due to the E1 and E1 plus Delta1 interband transitions of GaSb and InAs. For SLs with small InAs layer thickness (4 ML InAs/10 ML GaSb) the critical point energies are found to depend on the type of interfacial bonding, with an energy shift of up to 50 meV observed between SLs with GaAs- and InSb-like interfaces. Resonant Raman measurements show a pronounced enhancement in scattering efficiency for the superlattice phonons and, in particular, for the interface modes for incident photon energies matching the critical point energies of the SL