Size effect of parallel silicide contact

When two silicides with different Schottky barrier heights coexist at a silicide-Si interface, the apparent barrier-height measured by forward I-V characteristics depends not only on the fraction of the area of the low-barrier phase but on the size of the low-barrier phase. In this study, apparent barrier heights for varying size of the low-barrier phase have been obtained by numerical analysis of both Poisson's equation and the current continuity equation. The apparent barrier height approaches the mean value of Schottky-barrier heights weighted by the low- and high-barrier areas as the size of the low-barrier phase decreases to about five times the Debye length. When the size of the low-barrier phase is of the magnitude of 500 times or more the Debye length, the apparent barrier height approaches the value determined by the fraction of the area of low-barrier phase as reported earlier [I. Ohdomari and K. N. Tu, J. Appl. Phys. 51, 3735 (1981)].