MBE-growth and characterization of MeF/sub 2/ (Me=Mn,Zn)/Si heterostructures

Bulk manganese and zinc fluoride crystals have the same crystal structure but quite different electronic and magnetic properties. MnF/sub 2/ is insulator and well known antiferromagnetic; doped ZnF/sub 2/ is n-type semiconductor with wide (/spl sim/7eV) band gap, which is attractive for electroluminescence applications. Parameters of the rutile-type tetragonal structure of these materials do not match well to the silicon lattice. It is known, however that these fluorides have a number of metastable phases, which may much better fit to silicon substrate. We study growth, structural and optical properties of MnF/sub 2/ and ZnF/sub 2/ layers grown on Si substrates. To prevent etching of silicon surface by these fluoride molecules observed at elevated temperatures, CaF/sub 2/ buffer layer was used. It was found that MnF/sub 2/ crystallizes on CaF/sub 2/[111] and CaF/sub 2/[001] buffers in orthorhombic /spl alpha/-PbO/sub 2/-type phase (a=0.4953 nm, b=0.5798 nm, c=0.5362 nm) however the epilayers have multidomain structures in the accordance with the symmetry of the surface.