SLOW POSITRON-ANNIHILATION IN SILICIDE FILMS FORMED BY SOLID-STATE INTERACTION OF CO TI/SI AND CO/SI/

Slow positron beam was used to investigate the solid state reaction of Co/Si and Co/Ti/Si. Variable-energy (0-20 keV) positrons were implant ed into examples at different depths. The Doppler broadening of the an nihilation gamma-ray energy spectra measured at a number of different incident positron energies is characterised by a line-shape parameter, S. It was found that the measured S parameters are sensitive to thin film reaction and crystalline characteristics. In particular, the S pa rameter of epitaxial CoSi2 formed by the ternary reaction is quite dif ferent from that of the polycrystalline CoSi2 formed by direct reactio n of Co with Si.