Indexed on: 01 Nov '96Published on: 01 Nov '96Published in: Journal of Electronic Materials
The variations of Schottky barrier heights on Si1-x-y GexCy films with composition and strain have been investigated and compared to those expected for the band gap energy. The barrier on n-type does not depend on composition and strain. This independence suggests that the Fermi level at the interface between tungsten and Si1-x-yGexCy alloys (x≠0) is pinned relative to the conduction-band. For Si1-xGex the barrier on p-type follows the same trends as the band gap. For the ternary alloys, the variations of the barrier on p-type seem to be too 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 tensile as the deposition pressure increases. The absence of change in the barrier height of W to p-type-silicon and n-type-Sij xGex-films suggests that the Fermi level at the interface with Si is pinned relative to the valence-band while it is pinned relative to the conduction when Ge is added.