GROWTH OF BETA-FESI2 ON SILICON SUBSTRATES BY CHEMICAL BEAM EPITAXY

The deposition of FeSi2 thin films on Si(111) substrates by chemical beam epitaxy is described. Pure Si2H6 and Fe(CO)5 gases were used for the Si and Fe beams, respectively. Results of depositions at substrate temperatures between 400 and 550-degrees-C are given. A 160 angstrom thick film deposited at 400 and 500-degrees-C followed by thermal annealing at 600-degrees-C for 1 h exhibited no evidence of pinholes over the 2 inch diameter wafer. The layer consisted of crystalline grains of beta-FeSi2, 200-500 angstrom in diameter. High-resolution transmission electron microscopy of the layer revealed that the (110) or (101) planes of all the beta-FeSi2 grains observed were parallel to the Si(111) surface planes. Examination of many grains revealed the presence of all three equivalent azimuthal orientations expected from simple lattice mismatch theory. Additionally, the beta-FeSi2/Si(111) interface was abrupt for each grain and very smooth over the distance of tens of grains.