A novel phase was discovered by dual low-energy ion implantation and high vacuum electron beam annealing. (100) p-type Si was implanted with 20keV 12C+ ions to a fluence of 6 x 1016/cm2 and with 7keV Pb+ ions to a fluence of 4 x 1015/cm2. The 12C ion implantation resulted in a sub-stoichiometric shallow SiCx layer that intersected the surface. The implanted Pb ions decorated a shallow sub-surface region. High vacuum electron beam annealing at 1000C for 15s using a temperature gradient of 5C/s led to the formation of large SiC nanocrystals on the surface with RBS measurements showing that Pb had diffused into the deeper region affected by the 12C implantation. In this region, a new crystalline phase was discovered by XRD measurements.

Diffusion of Pb in Carbon Ion-Implanted Silicon - Discovery of a New Crystalline Phase after Electron Beam Annealing. A.Markwitz, H.Baumann, P.Davy, P.B.Johnson: Vacuum, 2008, 82[11], 1306-11