Electronic structure calculations were used to study the interaction of C with isolated substitutional dopants (B, P, or As), vacancies, and dopant-vacancy pairs in Ge. For comparison, equivalent defects were examined in Si. The calculations employed a plane-wave basis set and pseudopotentials within the generalized gradient approximation of density functional theory. The results predicted a range of different association preferences, with C being strongly bound in some cases and unbound in others. For example, in Ge, the C-vacancy cluster was weakly bound whereas in Si it was more strongly bound. Conversely, dopant-C pairs were not stable in either Ge or Si compared to their isolated components. If, however, they were formed during implantation, they will act as strong vacancy traps. Details of clusters comprised of a dopant, C, and vacancy were also discussed with respect to their formation by the association of a vacancy or cluster pair.

Carbon, Dopant and Vacancy Interactions in Germanium. A.Chroneos, B.P.Uberuaga, R.W.Grimes: Journal of Applied Physics, 2007, 102[8], 083707