Superconducting magnesium diboride films on Si with Tc0∼24 K grown via vacuum annealing from stoichiometric precursors

Superconducting magnesium diboride films with T(c0)similar to 24 K and sharp transition similar to1 K were prepared on Si by pulsed-laser deposition from stoichiometric MgB2 target. Contrary to previous reports, anneals at 630 degreesC and a background of 2x10(-4) Ar/4%H-2 were performed without the requirement of Mg vapor or Mg cap layer. This integration of superconducting MgB2 film on Si may thus prove enabling in superconductor-semiconductor device applications. Images of surface morphology and cross-section profiles by scanning electron microscopy show that the films have a uniform surface morphology and thickness. Energy-dispersive spectroscopy study reveals these films were contaminated with oxygen, originating either from the growth environment or from sample exposure to air. The oxygen contamination may account for the low T-c for those in situ annealed films, while the use of Si as a substrate does not result in a decrease in T-c as compared to other substrates. (C) 2001 American Institute of Physics.