Nanoscale Lead Inclusions in Silicon

Abstract

TEM analyses of Si implanted with immiscible elements have shown that the implanted species characteristically segregate to form nanoscale inclusions in the amorphous Si matrix. Subsequen annealing induced recrystallization was found to lead to simultaneous removal of nearly all of the implanted species, explained in terms of stress-induced trapping of the implanted atoms at the amc phous/crystalline interface as it progresses towards the surface.The solubility of Pb in Si is negligible, and it has previously been shown-that elemental nanoscale inclusions can be formed in Si either by ion implantation at elevated temperature or by rapid solidi cation. In the present work single crystals of <110> Si have been implanted with 80 keV Pb+ k at 300K, 625K and 925K respectively. The implanted fluence was 8-1019 m−2 corresponding to an average concentration of about 3 at.%. Combined TEM and RBS/channeling analysis showed that implantations at 300 K and 625 K induced amorphization of the implanted layer with dense distributions of nanoscale lead inclusions embedded in the amorphous silicon matrix (fig. 1).