As-grown MgB2 films were grown by MBE (Molecular Beam Epitaxy) apparatus on MgO(100) substrates under low-temperature and low-growth rate conditions using a molecular beam epitaxy. We confirmed the temperature range for MgB2 fabrication predicted by Liu et al. Under the conditions of substrate temperature 200 °C, B 0.03 nm/s and Mg/B=8, the films were highly c-axis oriented with a superconducting transition of 35 K. We measured the upper critical fields (Hc2) using a 30 T pulsed magnet and critical current density (Jc). Hc2 and Jc at 4.2 K were about 30 T and 10 MA/cm2, respectively.
