Reactive Schottky barrier formation: The Pd/Si interface

Abstract

The initial stages of Schottky barrier formation for Pd on Si have been studied on atomically clean Si (111) and (100) surfaces. Comparison with thick reactively formed Pd2Si films establishes that the work function and electronic state density at the interface are predominately associated with the formation of a Pd2Si-like compound. These surface properties (as well as the lattice constant) vary with film thickness and annealing history. The observed changes in surface work function, electronic density of states, and lattice constant can be simply understood on the basis of stoichiometry variations in the silicide film in which the Pd2Si crystal structure is maintained. These results illustrate how aspects of interface reactions (compound formation, stoichiometry variations, surface segregation, etc.) may complicate experimental studies of interface formation in other systems (such as Pd/GaAs). Preliminary studies of ’’real’’ interfaces (native-oxide-covered substrates) illustrate the additional complications present in studies of such systems.