Research On Fabrication And Properties Of β-FeSi 2 Thin Films By Sputting

Using RF-magnetron sputtering, we deposited Fe/Si multilayer by changing their thickness ratio on silicon and quartz substrates.β-FeSi₂ thin films were formed after annealing. The results indicate that multilayer with thickness ratio of Fe/Si equal to 20nm/64nm, 2nm/6.4nm and 1nm/3.2nm will change intoβphase iron disilicide on silicon substrates. However, additionalεphase formed in those on quartz substrates due to the lack of silicon. For films on both types of substrates, the surface roughnesses are small. The surface of the films is smooth when the sublayer becomes thicker. The films produced from 20nm/64nm structure have a homogeneous and dense surface, and have a good smoothness and continuing structure.We also prepared boron dopedβ-FeSi₂ films with elemental boron chips on silicon target surface by RF-magnetron sputtering on quartz substrates. The doping concentration was adjusted by varying the area ration of boron chips on silicon targets. In order to get single phase ofβ-FeSi₂ on quartz substrates, we increased the silicon content of the Fe/Si multilayer, the designed Fe/Si thickness ratio is 2.26nm/7.7nm. And the XRD patterns showed that thin films with single phase ofβ-FeSi₂ were obtained on quartz substrates with the B/Si area ration of 0, 2%, 3%, 5%. P type conductivity was measured by thermal probe. Beside, with the increasing of B/Si area ratio, the resistivity of the films decrease significantly, from 2.052Ω?cm to 0.021Ω?cm; and their band gap was narrowed down because of Boron doping. Films with a B/Si area ratio of 5% have the lowest resistivity (0.021Ω?cm), and the bad gap is 0.86eV.Finally, we used ion beam sputtering deposition to form Fe/Si multilayer with different ratioes of atoms on silicon and quartz substrates. Betterβ-FeSi₂ crystal quality was got after annealing. Probably owing to the characteristic of ion beams, films grown on quartz and silicon substrates display a preferred orientation of (422), which has rarely been reported. Because the atom ratio is larger and closest to 2,β-FeSi₂ films of 2nm/7.4nm multilayer have a homogeneous and dense surface with singleβ-FeSi₂ phase after annealing. A direct gap of 0.84eV was obtained by optical absorption measurement. The optical absorption coefficient is higher than 105cm-1 at 1.0 eV.