RESONANT RAMAN-SCATTERING AND SPECTRAL ELLIPSOMETRY ON INAS GASB SUPERLATTICES WITH DIFFERENT INTERFACES

We have used Raman spectroscopy and spectral ellipsometry to investiga te InAs/GaSb short-period superlattices (SLs), grown by molecular-beam epitaxy, with either InSb- or GaAs-like interfaces. Room-temperature ellipsometric measurements show spectral features in the dielectric fu nction due to the E1 and E1 + DELTA1 interband transitions of GaSb and InAs. For SLs with small InAs layer thicknesses (4 ML InAs/10 ML GaSb ) the critical point energies are found to depend on the type of inter facial bonding, with an energy shift of up to 50 meV observed between SLs with GaAs- and InSb-like interfaces. Resonant Raman measurements s how a pronounced enhancement in scattering efficiency for the superlat tice phonons and, in particular, for the interface modes for incident photon energies matching the critical point energies of the SL. (C) 19 94 American Institute of Physics.