Multiple phase structures of NiSi2 on Si(001): An atomic view.

Abstract

Three different growth structures of nickel silicide on the Si(001) were observed as functions of coverage and temperature. The structure of (2\ifmmode\times\else\texttimes\fi{}1) Si dimer bonds is formed at the interface before a bulklike (1\ifmmode\times\else\texttimes\fi{}1) structure is grown. The (2\ifmmode\times\else\texttimes\fi{}1) and (1\ifmmode\times\else\texttimes\fi{}1) structures coexist at the coverage of less than 1 ML. The (1\ifmmode\times\else\texttimes\fi{}1) structure contains many twin boundaries that can be developed into ``facetbars'' in a thicker film. High-temperature annealing induces a ($\sqrt{2}$\ifmmode\times\else\texttimes\fi{}$\sqrt{2}$)-R45\ifmmode^\circ\else\textdegree\fi{} structure with metallic character. Conflicting results in macroscopic Schottky barrier height measurements can be explained by coexistence of these three observed phases. \textcopyright{} 1996 The American Physical Society.