Impact ionization in GaAs: A screened exchange density-functional approach

Silvia Picozzi, R. Asahi, C. B. Geller, A. Continenza, Arthur J Freeman

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16 Citations (Scopus)

Abstract

Results are presented of a fully ab initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave method. The calculated impact ionization rates show a marked orientation dependence in k space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab initio calculations of pair production rates in new and more complex materials.

Original languageEnglish
Article number113206
Pages (from-to)1132061-1132064
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number11
Publication statusPublished - Mar 15 2002

ASJC Scopus subject areas

  • Condensed Matter Physics

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    Picozzi, S., Asahi, R., Geller, C. B., Continenza, A., & Freeman, A. J. (2002). Impact ionization in GaAs: A screened exchange density-functional approach. Physical Review B - Condensed Matter and Materials Physics, 65(11), 1132061-1132064. [113206].