"Relaxation effects on the negatively
charged Mg impurity in zincblende GaN ",
L.K. Teles, L.M.R. Scolfaro, J.R. Leite,
L.E. Ramos, A. Tabata, J.L.P. Castineira, and D.J. As,
phys. stat. sol. (b) 216 ,
541 (1999).
The electronic structure of Mg impurity in zincblende
(c-) GaN is investigated by using ab initio full potential linear-augmented
plane-wave method and the local density-functional approximation. Full geometry
optimization calculation, including nearest and next-nearest neighbor displacements
are performed for the impurity in the neutral and negatively charged states.
A value of 190 +/- 10 meV was obtained for the Franck-Condon shift to the
thermal energy, which is in good agreement with that observed in recent
low temperature photoluminescence and Hall-effect measurements. We conclude
that the nearest and next-nearest neighbors of the Mg impurity replacing
Ga in c-GaN undergo outward relaxations which play an important role in
the determination od the center acceptor energies.