Abstract
Based on measurements of angle-resolved photoemission, we report that in the Pb/Ge (111) -√3×√3 R30° structure, in addition to three bands resembling Ge heavy hole (HH), light hole (LH), and split off (SO) bulk band edges, a fourth dispersive band resembling the nonsplit off (NSO) band is found near the surface zone center. While three Ge bulklike bands get distorted due to strong coupling between Pb and Ge, the NSO-like band gets weaker and disappears for larger thickness of Pb, which, when combined with ab initio calculations, indicates its localized nature within space-charge layer. Our results are clearly important for designing electronics involved with metal-semiconductor contacts. © 2010 The American Physical Society.