Photoemission measurements of surface states for cleaved and annealed Ge(111) surfaces

Abstract

The electronic surface states of cleaved and the annealed Ge(111) surfaces have been investigated by photoemission measurements using ultraviolet light. From the energy distribution curves of photoelectrons, the surface states of cleaved Ge are found to form a single band centered at 0.7 eV below the valence-band maximum, $E_{Vmax}$, with half-width of 0.7 eV. By annealing at 100°C, two bands centered at 0.7 and 0.3 eV below $E_{Vmax}$ have been observed, and by annealing at 300°C, only the latter has been observed.