Layer-by-layer electronic structure at semiconductor-metal interfaces: band gap and magnetism

Epitaxial semiconductor-metal interfaces are studied with inverse photoemission. For Group-V elements (Sb,Bi) on III-V surfaces (GaAs(110),InP(110)) it is possible to distinguish electronic states of the first few layers. The metal layer at the interface becomes semiconducting. Interfaces of semiconductors with ferromagnetic metals, such as epitaxial GaAs(110)Fe, exhibit a change in magnetism. The ferromagnetic exchange splitting can be resolved very clearly in Fe by inverse photoemission. The bulk splitting of 2 cV is observed to collapse to < 0.7 eV for a monolayer of Fe on GaAs(110), probably due to FeAs bonding. It is suggested to use Au as an epitaxial barrier layer between GaAs and Fe since it is lattice-matched and does not suppress magnetism at the interface. Gold also plays the role of a surfactant, thereby making it possible to grow Fe in a layer-by-layer fashion. © 1992.