Transverse-momentum selection rules for ballistic electrons at epitaxial metal/GaAs(001) interfaces

International audience; We report on ballistic electron-emission spectroscopy on high-quality Au(110)/GaAs(001) and Fe(001)/GaAs(001) Schottky contacts. For the Au(110)/GaAs(001) interface, the ballistic current is characterized by a strong electron injection in the L valley of the GaAs conduction band. This remarkable spectroscopic feature is absent for the Fe(001)/GaAs(001) interface. These observations are explained by the different electronic structures in the two metal layers, assuming conservation of the electron transverse momentum at the metal/semiconductor epitaxial interfaces. Conversely, this comparative study suggests that the technique can be used for the analysis of local electronic states propagating in the metal films.