Field penetration and band bending near semiconductor surfaces in high electric fields

The existing theory of band bending in the surface space charge region of semiconductors is adapted to problems in field emission, field ionization and field evaporation. The surface field in the space charge layers of semiconductors appropriate for these phenomena ranges from ~10−2 V/Å to a few 10−1 V/Å, similar to those encountered in many interface phenomena involving semiconductors. We found that the surface potential resulting from band bending may amount to a few eV. The field penetrates ~10 Å into the semiconductor surface for intrinsic cases, and ~200Å for an n-type semiconductor in a positive field, or for a p-type semiconductor in a negative field. Both the surface potential and the field penetration will affect significantly the electronic properties of the near surface layers. In particular, the photon adsorption edge will be shifted toward the red by the field penetration effect.