Nature 444, 465-468 (23 November 2006) | doi:10.1038/nature05340; Received 29 June 2006; Accepted 9 October 2006

Superconductivity in doped cubic silicon

E. Bustarret1,7, C. Marcenat3,7, P. Achatz1,3, J. Kac caronmarc caronik1,4, F. Lévy3, A. Huxley3,8, L. Ortéga2, E. Bourgeois5, X. Blase5, D. Débarre6 & J. Boulmer6

  1. Laboratoire d'Etudes des Propriétés Electroniques des Solides,
  2. Laboratoire de Cristallographie, CNRS, BP166, 38042 Grenoble, France
  3. Département de la Recherche Fondamentale sur la Matière Condensée, SPSMS, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble, France
  4. Institute of Experimental Physics, Slovak Academy of Sciences, SK-04001 Kos caronice, Slovakia
  5. Laboratoire de Physique de la Matière Condensée et Nanostructures, Université Lyon I and CNRS, Domaine scientifique de la Doua, 69622 Villeurbanne, France
  6. Institut d'Electronique Fondamentale, Université Paris Sud and CNRS, Bât. 220, 91405 Orsay, France
  7. These authors contributed equally to this work.
  8. Present address: School of Physics, University of Edinburgh, Edinburgh EH9 3JZ, UK.

Correspondence to: E. Bustarret1,7C. Marcenat3,7 Correspondence and requests for materials should be addressed to E. Bu. (Email: etienne.bustarret@grenoble.cnrs.fr) and C.M. (Email: christophe.marcenat@cea.fr).

Although the local resistivity of semiconducting silicon in its standard crystalline form can be changed by many orders of magnitude by doping with elements, superconductivity has so far never been achieved. Hybrid devices combining silicon's semiconducting properties and superconductivity have therefore remained largely underdeveloped. Here we report that superconductivity can be induced when boron is locally introduced into silicon at concentrations above its equilibrium solubility. For sufficiently high boron doping (typically 100 p.p.m.) silicon becomes metallic1. We find that at a higher boron concentration of several per cent, achieved by gas immersion laser doping, silicon becomes superconducting. Electrical resistivity and magnetic susceptibility measurements show that boron-doped silicon (Si:B) made in this way is a superconductor below a transition temperature Tc approximately 0.35 K, with a critical field of about 0.4 T. Abinitio calculations, corroborated by Raman measurements, strongly suggest that doping is substitutional. The calculated electron–phonon coupling strength is found to be consistent with a conventional phonon-mediated coupling mechanism2. Our findings will facilitate the fabrication of new silicon-based superconducting nanostructures and mesoscopic devices with high-quality interfaces.

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