Nanostructuring at the surface of low-energy lead-implanted silicon by electron beam annealing

Low-energy lead ion implantation and high-temperature electron beam annealing were used to study the potential of producing Pb nanostructures on Si. Pb(+) ions were implanted at high dose into p-type (100) Si to the depth of 8.0 nm. The implanted samples were annealed under high vacuum conditions with an electron beam at 200-700 degrees C for 15 s. Rutherford Backscattering Spectrometry (RBS) shows rapid out-diffusion of Pb atoms above 400 degrees C. However, some Pb atoms are still present in the near-surface region after annealing the implanted samples at 700 degrees C. Lead nanostructures were found on samples annealed above 300 degrees C. Annealing the samples at 450 degrees C causes the formation of nanostructures as tall as 4.1+/-0.1 nm. Many of these are arranged in 'web-like' strings that extend over micrometer distances. Occasionally, much larger nano-features (as wide as 500 nm in diameter, average height of 1.5 nm) appear in the centre of the strings. Annealing samples well above the melting point of lead results in randomly distributed small nanometer-sized Si nano-dots. Copyright (C) 2008 John Wiley & Sons, Ltd.