Determination of the nitrogen vacancy as a shallow compensating center in GaN doped with divalent metals

We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-...

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Bibliographic Details
Published in:Physical review letters 2015-01, Vol.114 (1), p.016405-016405, Article 016405
Main Authors: Buckeridge, J, Catlow, C R A, Scanlon, D O, Keal, T W, Sherwood, P, Miskufova, M, Walsh, A, Woodley, S M, Sokol, A A
Format: Article
Language:English
Subjects:
Defects
Dopants
Doping
Energy of formation
Gallium nitrides
Ionization
Localization
Vacancies
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Summary:We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-defined reference level. Defect formation and ionization energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p-type conductivity in GaN and the associated major spectroscopic features, including the ubiquitous 3.46 eV photoluminescence line, a characteristic of all lightly divalent-metal-doped GaN materials that has also been shown to occur in pure GaN samples. Our results give a comprehensive explanation for the observed behavior of GaN doped with low concentrations of divalent metals in good agreement with relevant experiment.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.114.016405