SCHOTTKY-BARRIER HEIGHTS ON IV-IV COMPOUND SEMICONDUCTORS

The variations of Schottky barrier heights on Si-1-x-y GexCy films wit h composition and strain have been investigated and compared to those expected for the band gap energy. The barrier on n-type does not depen d on composition and strain. This independence suggests that the Fermi level at the interface between tungsten and Si1-x-yGexCy alloys (x no t equal 0) is pinned relative to the conduction-band. For Si-1-x Ge-x, the barrier on p-type follows the same trends as the band gap. For th e ternary alloys, the variations of the barrier on p-type seem to be t oo large? to be only due to a variation of the band-gap. In addition, we have investigated the influence of the deposition conditions of the sputtered-W-gate on the barrier to silicon and Si1-xGex, Our results show that the barrier on n-type-Si and p-type-Si1-xGex-films increases when the stress retained in the W-films changes from compressive to t ensile as the deposition pressure increases. The absence of change in the barrier height of W to p-type-silicon and n-type-Si1-xGex-films su ggests that the Fermi level at the interface with Si is pinned relativ e to the valence-band while it is pinned relative to the conduction wh en Ge is added.