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

Abstract

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 E 1 energy gap.