  We introduce a simple method of an MgB2 film preparation using sequential
electron-beam evaporation of B-Mg two-layer (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 the
superconducting transition only. The MgB2 films obtained, about 200 nm thick,
exhibit a maximum zero resistance critical temperature of 36 K and critical
current density of 3x10^7 A/cm^2 at 13.2 K
