Diffusion of Pb in carbon ion-implanted silicon: Discovery of a new crystalline phase after electron beam annealing

A novel phase has been discovered by dual low-energy ion implantation and high vacuum electron beam annealing. (100) p-type Si was implanted with (a) 20 keV 12C+ ions to the fluence of 6 × 1016 cm−2 and (b) 7 keV Pb+ ions to the fluence of 4 × 1015 cm−2. The 12C ion implantation results in an understoichiometric shallow SiCx layer that intersects with the surface. The implanted Pb ions decorate a shallow subsurface region. High vacuum electron beam annealing at 1000 °C for 15 s using a temperature gradient of 5 °C s−1 leads to the formation of large SiC nanocrystals on the surface with RBS measurements showing Pb has diffused into the deeper region affected by the 12C implantation. In this region, a new crystalline phase has been discovered by XRD measurements.