Electron impact ionization in p-type degenerate narrow-gap semiconductors with a Kane band dispersion law

摘要

Impact ionization of the heavy-hole band by electrons in a degenerate p-type Kane semiconductor is studied theoretically under the condition that the hole temperature is much less than their Fermi energy. We take into consideration for the first time the fact that the valence band states that could be ionized in a non-degenerate material by an electron at the ionization threshold may be empty in a degenerate p-type semiconductor if the Fermi level lies deep enough in the valence band. Therefore the actual ionization threshold energy in this material depends on the Fermi level position. We found this dependence and calculated analytically the corresponding impact ionization probability as a function of the ionizing electron energy and the Fermi level position.