Ab initio study of substitutional nitrogen in GaAs

Ferraz, AC

Abstract

We investigate the atomic geometry, formation energies, and electronic structure of nitrogen occupying both arsenic and gallium sites in GaAs (N-As and N-Ga) using first-principles total-energy calculations. We find that both neutral defects induce impurity-like empty levels in the band gap acting as acceptors. While N-As shows a s-like a(1) level in the middle of the band gap, N-Ga shows a p-like t(2) level close to the bottom of the conduction band. The gap level of N-As gives theoretical support for the experimentally observed band-edge redshift on the GaAsN alloy for a N concentration similar to3%. Strong inward relaxations preserving the T-d symmetry characterize the N-As equilibrium geometry in all the charge states investigated. In contrast, N-Ga exhibits a structural metastability in neutral charge state and Jahn-Teller off-center distortions in negative charge states forming a negative-U center. Formation energies of competing N-As and N-Ga defects are also discussed. (C) 2001 American Institute of Physics.

Más información

Título según WOS: ID WOS:000167151000021 Not found in local WOS DB
Título de la Revista: APPLIED PHYSICS LETTERS
Volumen: 78
Número: 9
Editorial: AIP Publishing
Fecha de publicación: 2001
Página de inicio: 1231
Página final: 1233
DOI:

10.1063/1.1351524

Notas: ISI