EXAFS INVESTIGATION OF CO SITES IN COSI2 FILM GROWN BY ION-BEAM-ASSISTED DEPOSITION

We report Extended X-ray Absorption Fine Structure (EXAFS) analyses at the Co k-edge of CoSi2 thin films grown by Ion Beam Assisted Depositi on (IBAD). CoSi2 was obtained by Co evaporation onto amorphous Si at 4 90 degrees C, while a 1 keV Ar+ ion beam irradiated the substrate. The EXAFS spectra were fitted using the GNXAS software, taking into accou nt the multiple scattering contribution. The influence of the IBAD pro cess on the local structure around the Co sites was studied and relate d to the electrical resistivity of the films. Our results show that IB AD technique improves the stoichiometry of CoSi2 with respect to non-a ssisted growth at the same temperature, but also produces local damage which is responsible for an increase of the electrical resistivity. F inally, the role of the Ar+ ion current density was investigated, and a strong improvement of both local structural order and resistivity fo r high beam currents is reported.