Impact Ionization in GaAs within A Screened Exchange Density Functional Formalism

S. Picozzi, R. Asahi, C. B. Geller, A. J. Freeman

Research output: Contribution to journalArticlepeer-review


We present the results of a fully first-principles calculation of impact ionization rates in GaAs within the density functional theory formalism, using a screened-exchange approach and the highly accurate all-electron full-potential linearized augmented plane wave (FLAPW) 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
Pages (from-to)421-424
Number of pages4
JournalJournal of Computational Electronics
Issue number3
Publication statusPublished - Oct 1 2002


  • density functional theory
  • GaAs
  • impact ionization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Modelling and Simulation
  • Electrical and Electronic Engineering

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