The correlation of Schottky barrier height and microstructure has been investigated for three different epitaxial Ni-silicides, type-A, type-B NiSi2 and NiSi, on n-Si 111). All these interfaces can be formed to yield a barrier height of 0.78 eV. This high barrier is obtained only for interfaces with almost perfect structures; otherwise less perfect interfaces formed with improper annealing or impurity incorporation yielded low barrier heights of 0.66 eV. The barrier seems to be primarily controlled by the degree of structural perfection, instead of the stoichiornetry and the specific type of epitaxy at the interface. A low interface state density can explain the sensitivity of the barrier height of near-perfect interfaces on minor amounts of impurities, defects, and structural imperfections. © 1986, American Vacuum Society. All rights reserved.