The formation of the Schottky barrier at the V/Si interface

Synchrotron radiation photoemission measurements have been used to study the behavior of the Schottky barrier height φbn and electronic structure of the V/Si interface for both cleaved Si(111)–(2×1) and sputter-cleaned Si(111)–(7×7) surfaces. Although the Schottky barrier height φbn of the clean surface is influenced by surface reconstruction (and by steps), the barrier becomes pinned at low (∠2 Å) V coverage at a position essentially independent of the initial clean surface structure. Formation of the bulk V metal band structure is not complete until ∠30–40 Å V coverage, indicating coverage-dependent structural effects in the growth of the metal film. These effects also seem to produce secondary influences on φbn , which are manifested as a gradual increase of φbn with higher coverage or mild (∠200 °C) annealing. However, upon higher temperature annealing (?350 °C) the trend reverses, with φbn decreasing to a value (∠0.64 eV) characteristic of the bulk VSi2 contact which is formed at 500–550 °C; this change in the behavior of φbn is directly correlated with the onset of atomic mixing across the interface.