Correlation of the interfacial structure and electrical properties of epitaxial silicides on Si

Abstract

The Schottky barrier height (SBH) measured at epitaxial NiSi2 contacts is shown to be strongly influenced by the local interfacial structure. Diodes with guard rings, which eliminate the edge leakage current which has hampered some previous studies, were prepared by molecular-beam epitaxy of NiSi2 films on a wide range of n- and p-type doped Si substrates. Schottky diodes processed with high quality NiSi2 films on Si(111) are shown to exhibit highly ideal electrical properties. Structural inhomogeneity at the NiSi2/Si(100) interface is shown to lead to electrical properties which are consistent with the existence of spatial inhomogeneity in the SBH. Numerical simulations of the electron transport across the inhomogeneous diodes, based on a spatial variation of the interfacial SBH consistent with the observed structural inhomogeneity in the films, are shown to accurately reproduce the trends in the electrical behavior of the inhomogeneous diodes. The necessity to understand the interfacial atomic structure at metal/semiconductor contacts in order to understand the formation mechanism of the Schottky barrier is stressed by these results.