Photoemission measurement of the potential step created at InAs/GaAs junctions by interfacial silicon

Photoemission measurements at the InAs/GaAs (001) interfaces following insertion of interfacial silicon reveal large core-level shifts. For InAs-on-GaAs junctions, Si-induced potential steps across the interface, up to 0.2 eV for one monolayer of Si, have been clearly identified and correspond to an increase of the valence-band offset. No deviation of the morphology from the planned structure on the atomic scale is detected. On the other hand, GaAs-on-InAs junctions and GaAs/InAs/GaAs ‘‘quantum wells’’ are somewhat diffuse due to segregation of In to the surface during growth, which perturbs the effect of interfacial Si. This case exemplifies the influence of the atomic structure of the junction on this effect.