Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State

A. Lim, W. M.C. Foulkes, A. P. Horsfield, D. R. Mason, A. Schleife, E. W. Draeger, A. A. Correa

Research output: Contribution to journalArticlepeer-review


We use time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from 1 eV to 100 keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

Original languageEnglish (US)
Article number043201
JournalPhysical review letters
Issue number4
StatePublished - Jan 27 2016
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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