Fluorine-vacancy complexes were directly observed in the Si0.94Ge0.06 layer in a Si-SiGe-Si structure, using variable-energy positron annihilation spectroscopy. These complexes were linked to the significant reduction of B diffusion in the SiGe layer via interstitial trapping. Vacancies were introduced into the samples by ion implantation with 185keV F+ to doses in the range of 9 x 1014 to 1016/cm2; the samples were subsequently subjected to rapid annealing in N ambient at 950C for 30s. The variable-energy positron annihilation spectroscopy results, in combination with F profiles obtained by secondary ion mass spectrometry, were consistent with F4nVn complexes being associated with the SiGe layer and that they preferentially accumulate at the Si/SiGe interfaces. Their concentration was critically dependent on annealing temperature, decreasing significantly after annealing at 1000C.

Fluorine-Vacancy Complexes in Si-SiGe-Si Structures. D.A.Abdulmalik, P.G.Coleman, H.A.W.El Mubarek, P.Ashburn: Journal of Applied Physics, 2007, 102[1], 013530