Inverse-photoemission studies of si and iii-v compounds

Resolved inverse-photoemission spectroscopy is used to measure the energy dispersion E (k) of the unoccupied electronic surface-state bands of Si(111)2 × 1, Si(111)1 × 1-Ge, GaP(110), and GaAs(110). Comparison with optical transitions between occupied and empty surface states is made by measuring the bulk valence-band states in-situ with ultraviolet-photoemission spectroscopy. This procedure gives larger surface band gaps than the optical results and the discrepancy increases in going from Si(111)2 × 1 to GaAs(110). © 1989 IOP Publishing Ltd.