Study of the inhomogeneity of Schottky barrier height in nickel silicide by the internal photoemission spectroscopy

The inhomogeneity of Schottky barrier height (SBH) in nickel silicide/Si contacts was observed by the internal photoemission spectroscopy. New Fowler equations were introduced to analyze the observed properties. We assumed that two or three regions with different SBHs coexist in Ni silicide/Si contacts, and then the individual barrier height was evaluated. We found that SBH increases monotonously with the increase of annealing temperature in the case of T-annealing < 600 degrees C. When T-annealing is 600 degrees C, SBH becomes maximal, then decreases monotonously with the increase of annealing temperature in the case of T-annealing > 600 degrees C. The formation of the two regions (Regions II and III) in nickel silicide/Si Schottky contacts annealed at different temperatures, was explained by the model of the Fermi-level pinning or the metal-induced gap states.