Electrical and structural properties of MgB2 films prepared by sequential deposition of B and Mg on the NbN-buffered Si(100) substrate

We introduce a simple method of a MgB2 film preparation using a sequential electron-beam evaporation of B-Mg bilayer (followed by in-situ annealing) on the NbN-buffered Si(100) substrate. The transmission electron microscopy analyses confirm a growth of homogeneous nanogranular MgB2 films without the presence of crystalline MgO. A sensitive measurement of temperature dependence of microwave losses shows a presence of intergranular weak links close to the superconducting transition only. The MgB2 films obtained, about 200-nm thick, exhibit a maximum zero resistance critical temperature of 36 K and a critical current density of 3x10(7) A/cm(2) at 13.2 K. (C) 2004 American Institute of Physics.