It was noted that vacancy-type defects such as divacancies (V2) and E-centers (P–V, Sb–V pairs) were the most common radiation defects in n-type Si and SiGe after ion implantation. It was known that V2 and P–V exhibited preferential configurations in the SiGe system with respect to the numbers of Ge atoms surrounding the defect. The stability of vacancy-type defect complexes (V2 and P–V pairs) was studied here as a function of pressure and the number of Ge atoms in the vicinity of a point defect in Si. The methods used were a molecular static method involving the Tersoff many-body interatomic potential, and an ab initio approach. It was found that the formation energies for a vacancy and divacancy, having a Ge atom in the nearest neighbourhood, were lowered by 1.42 and 1.76eV with respect to those in pure Si. The introduction of one more Ge atom as the neighbour of a vacancy or divacancy did not cause any change in the formation energy. For all types of defect considered, the formation energy had a tendency to decrease with increasing pressure.

Formation and Stability of Radiation Defect Complexes in Si and Si:Ge - Composition and Pressure Effects. M.Ganchenkova, A.Nazarov, A.Kuznetsov: Nuclear Instruments and Methods in Physics Research B, 2003, 202, 107-13