Anharmonic lattice relaxation during nonradiative carrier capture

Sunghyun Kim, Samantha N. Hood, Aron Walsh

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Lattice vibrations of point defects are essential for understanding nonradiative electron and hole capture in semiconductors as they govern properties including persistent photoconductivity and the Shockley-Read-Hall recombination rate. Although the harmonic approximation is sufficient to describe a defect with small lattice relaxation, for cases of large lattice relaxation it is likely to break down. We describe a first-principles procedure to account for anharmonic carrier capture and apply it to the important case of the DX center in GaAs. This is a system where the harmonic approximation grossly fails. Our treatment of the anharmonic Morse-like potentials accurately describes the observed electron capture barrier, predicting the absence of quantum tunneling at low temperature, and a high hole capture rate that is independent of temperature. The model also explains the origin of the composition-invariant electron emission barrier. These results highlight an important shortcoming of the standard approach for describing point defect ionization that is accompanied by large lattice relaxation, where charge transfer occurs far from the equilibrium configuration.

Original languageEnglish
Article number041202
JournalPhysical Review B
Volume100
Issue number4
DOIs
Publication statusPublished - 2019 Jul 22

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Point defects
Crystal lattices
electron capture
point defects
Lattice vibrations
Electrons
Electron emission
Photoconductivity
Ionization
harmonics
Charge transfer
Morse potential
lattice vibrations
Semiconductor materials
approximation
photoconductivity
Temperature
Defects
electron emission
breakdown

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Kim, Sunghyun ; Hood, Samantha N. ; Walsh, Aron. / Anharmonic lattice relaxation during nonradiative carrier capture. In: Physical Review B. 2019 ; Vol. 100, No. 4.
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Anharmonic lattice relaxation during nonradiative carrier capture. / Kim, Sunghyun; Hood, Samantha N.; Walsh, Aron.

In: Physical Review B, Vol. 100, No. 4, 041202, 22.07.2019.

Research output: Contribution to journalArticle

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