  Superconducting MgB2 thin films were prepared on Al2O3(0001) and MgO(100)
substrates. Boron thin films were deposited by the electron-beam evaporation
followed by post-annealing process with magnesium. Proper post annealing
conditions were investigated to grow good superconducting MgB2 thin films. The
X-ray diffraction patterns showed randomly orientated growth of MgB2 phase in
our thin films. The surface morphology was examined by scanning electron
microscope (SEM) and atomic force microscope (AFM). Critical current density
(Jc) measured by transport method was about 10^7 A/cm^2 at 15 K, and
superconducting transition temperature (Tc) was ~ 39 K in the MgB2 thin films
on Al2O3.
