For the sake of perspective, an overview is given of the development of concepts concerning the mechanism involved in Schottky barrier (SB) formation. Until about 1972 principally "macroscopic" data (e.g., I-V and C-V electrical measurements) were available. More recently "atomic" level microscopic tools have been increasingly applied experimentally to the problem of understanding SB formation. The most popular models for the III-V semiconductors are examined in terms of the metal:III-V chemistry including its correlation with barrier height and/or the effect of metal thickness. Experimentally it is found that, for most metals, the Schottky barrier pinning is completed with the deposition of less than a monolayer of metal. Most importantly, the Fermi level pinning position at these low metal coverages is found to correspond well with the SB height obtained from I-V measurements from carefully prepared samples with thicknesses of about 1000 Å. On the other hand, the metal:III-V chemistry appears to have little effect on the SB height. For example, four metals - Ag, Au, Cu, and Pd - have very different chemistry (varying from essentially no reaction for Ag to a very strong reaction for Pd); however, they give almost identical SB heights. After comparison of experimental data with various currently popular models, only a refined version of the united defect model is found consistent with the available data.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry