As-grown superconducting MgB2 thin films prepared by molecular beam epitaxy

Superconducting thin films of magnesium diboride (MgB2) were prepared on various substrates [SrTiO3 (001), sapphire R, sapphire C and Si (111)] by molecular beam epitaxy. The growth temperature was examined in the ambient to 650 °C. Only films formed at temperatures between 150 and 320 °C showed superconductivity. The best TConset of 36 K with a sharp transition width of ∼1 K was observed. The TC of the as-grown superconducting MgB2 thin films is close to the bulk value.