Superconducting properties of laser annealed implanted Si:B epilayers

We report on the superconducting properties of heavily doped silicon epilayers obtained by the implantation of B atoms in silicon wafers and subsequent laser annealing (pulsed laser induced epitaxy). A critical temperature similar to 250 mK has been obtained for samples with a boron concentration (c(B)) ranging from 2 to 10 at.%, which were checked by atom probe tomography to be free of any significant boron clustering. The standard dopant implantation technique is therefore an alternative (with respect to gas immersion laser doping) process to induce superconductivity in boron-doped silicon. Superconductivity was not observed with any of the other implanted dopants (P, As, Al) with similar concentrations down to 50 mK.