First-principles plane-wave pseudopotential local-density theory was used to model In sites. The most stable site involved In which was located at an off-center substitutional position, between 2 adjacent C vacancies. This was thought to be the most stable fundamental defect which formed following implantation. Initial formation of this center was associated with two C interstitials. However, the total energy of such a defect was significantly higher than that without C interstitials. Thus, only after these C interstitial atoms were removed by annealing would it be possible to observe the most stable predicted form of the In defect. This had a VC-In-VC [111] structure, and was expected to be associated with an observed 117MHz quadrupole frequency.

B.P.Doyle, J.K.Dewhurst, J.E.Lowther, K.Bharuth-Ram: Physical Review B, 1998, 57[9], 4965-7