Reemitted-positron spectroscopy of cobalt and nickel silicide films.

Reemitted-positron spectroscopy (RPS) has been employed in a systematic investigation of the positronic properties of the various phases (M 2 Si, MSi, and MSi 2 ) of Co and Ni silicide folms grown in situ on Si substrates. The positron work function O + is found to be negative for all of the different phases, with the parameter Σ≡μ - +μ + having a surprisingly large variation