Characterization of heterointerfaces and surfaces in InSb on GaAs and in InAs/AlSb quantum wells

Resonant Raman scattering by longitudinal optical (LO) phonons and by interface modes was used to study InSb/GaAs and InAs/AlSb heterointerfaces for InSb on GaAs and for InAs/AlSb quantum wells respectively, grown by molecular beam epitaxy. Raman spectra recorded from samples with InSb layers ranging in thickness from 10 to 300 monolayers indicate that, to achieve two dimensional growth of InSb on GaAs with good crystalline quality, the layer thickness must exceed around 100 monolayers. From the dependence on excitation power of electric-field-induced LO phonon scattering measured for a series of n- and p-type doped thick InSb layers, it is concluded that the surface Fermi level is pinned at the valence band edge. In InAs/AlSb quantum wells, scattering by an InSb-like interface mode is observed which resonates at approximately the InAs E1 energy gap.