  Superconductivity was discovered in heavily boron-doped diamond thin films
deposited by the microwave plasma assisted chemical vapor deposition (MPCVD)
method. Advantages of the MPCVD deposited diamond are the controllability of
boron concentration in a wide range, and a high boron concentration, especially
in (111) oriented films, compared to that of the high-pressure high-temperature
method. The superconducting transition temperatures are determined to be 8.7K
for Tc onset and 5.0K for zero resistance by transport measurements. And the
upper critical field is estimated to be around 7T.
