Electric-Field Dependence of the Surface Dipole of Semiconductors

Modulation of photoemission from $n$-type GaSb by additional light leads to the conclusion that the surface dipole (i.e., the electron affinity and the ionization energy) of semiconductors is influenced by the electric field of the space charge. Comparison of calculated with observed modulation yields an escape depth of 100 Å for photoelectrons from clean surfaces.