Superconducting magnesium diboride films on Si with T-c0 similar to 24 K grown via vacuum annealing from stoichiometric precursors

Superconducting magnesium diboride films with T(c0)similar to 24 K and shar p transition similar to1 K were prepared on Si by pulsed-laser deposition f rom stoichiometric MgB2 target. Contrary to previous reports, anneals at 63 0 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 superconducti ng MgB2 film on Si may thus prove enabling in superconductor-semiconductor device applications. Images of surface morphology and cross-section profile s by scanning electron microscopy show that the films have a uniform surfac e morphology and thickness. Energy-dispersive spectroscopy study reveals th ese films were contaminated with oxygen, originating either from the growth environment or from sample exposure to air. The oxygen contamination may a ccount for the low T-c for those in situ annealed films, while the use of S i as a substrate does not result in a decrease in T-c as compared to other substrates. (C) 2001 American Institute of Physics.