Energy-resolved momentum densities for the valence band of a nanoscale Si single crystal

We have measured the energy- and momentum-resolved band structure, and grou nd state of occupation of the bands, for a crystalline silicon sample along the ( 100) and ( 110) directions. Band structures were determined directly by the technique of electron momentum spectroscopy (EMS) for a self-suppor ting Si membrane with a thickness of approximately 7 nm. We compare our exp erimental results with nb initio calculations for bulk crystalline silicon performed within the linear muffin tin orbital approximation. Qualitative a greement is seen between experiment and theory for the main valence band pe ak. Additional intensity is observed in the measurement on either side of t he main peak and is attributed mainly to multiple-scattering events. Satell ite structure could also be present in these additional features, although there is no direct evidence for this.