Electron scattering due to threading edge dislocations in n-type wurtzite GaN

Jeong Ho You, Jun Qiang Lu, Harley T Johnson

Research output: Contribution to journalArticle

Abstract

The effect of electrically active V Ga-O N threading edge dislocations on drift and Hall mobilities in n-type epitaxial wurtzite (WZ) GaN is investigated theoretically. The charge distribution along the dislocation core is first obtained by means of a density-functional theory atomistic calculation; the two N atoms near the missing Ga atom at the dislocation core are found to be electron acceptors. An accurate analytical expression for dislocation electrostatic strength is then derived for the case of up to -2q charge per structural unit of the threading dislocation core. This strength factor is determined by minimizing the total increase of free energy per site of the partially charged dislocation line. Two different models of scattering potentials for charged dislocation lines are then used to determine the dislocation effect on in-plane electron mobility, and closed-form solutions for the dislocation contribution to drift and Hall mobilities are derived for the more accurate potential. By estimating the effects of other scattering mechanisms, the total mobility is then compared with available experimental data. It is found that for free-carrier concentrations higher than 10 16cm -3, reducing dislocation density below n dis=10 8cm -2 has little beneficial effect on total mobility for typical WZ GaN samples.

Original languageEnglish (US)
Article number033706
JournalJournal of Applied Physics
Volume99
Issue number3
DOIs
StatePublished - Feb 1 2006

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edge dislocations
wurtzite
electron scattering
scattering
electron mobility
charge distribution
atoms
estimating
free energy
electrostatics
density functional theory

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Electron scattering due to threading edge dislocations in n-type wurtzite GaN. / You, Jeong Ho; Lu, Jun Qiang; Johnson, Harley T.

In: Journal of Applied Physics, Vol. 99, No. 3, 033706, 01.02.2006.

Research output: Contribution to journalArticle

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N2 - The effect of electrically active V Ga-O N threading edge dislocations on drift and Hall mobilities in n-type epitaxial wurtzite (WZ) GaN is investigated theoretically. The charge distribution along the dislocation core is first obtained by means of a density-functional theory atomistic calculation; the two N atoms near the missing Ga atom at the dislocation core are found to be electron acceptors. An accurate analytical expression for dislocation electrostatic strength is then derived for the case of up to -2q charge per structural unit of the threading dislocation core. This strength factor is determined by minimizing the total increase of free energy per site of the partially charged dislocation line. Two different models of scattering potentials for charged dislocation lines are then used to determine the dislocation effect on in-plane electron mobility, and closed-form solutions for the dislocation contribution to drift and Hall mobilities are derived for the more accurate potential. By estimating the effects of other scattering mechanisms, the total mobility is then compared with available experimental data. It is found that for free-carrier concentrations higher than 10 16cm -3, reducing dislocation density below n dis=10 8cm -2 has little beneficial effect on total mobility for typical WZ GaN samples.

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