An investigation of the electrical and optical properties of thin iron layers grown on the epitaxial Si(111)-(2 × 2)-Fe phase and on an Si(111)7 × 7 surface.

Electrical and optical properties of thin iron layers grown at room temperature on the epitaxial silicide Si(111)-(2 × 2)-Fe phase and on an Si(111)7 × 7 surface were investigated using in situ Hall effect registration, atomic force microscopy, and optical spectroscopy. It was established that Si(111)-(2 × 2)-Fe phase has semiconducting properties with a 0.99 eV effective band gap and acts as a diffusion barrier for the deposited iron atoms, preventing intermixing with the substrate at room temperature. Peculiarities in the optical spectra of a sample with a 2 nm iron film grown on the Si(111)-(2 × 2)-Fe phase typical for both metal and semiconducting natures prove a conservation of the phase under the iron layer. The process of iron growth on the Si(111)-(2 × 2)-Fe phase is accompanied by the development of high stress in the subsurface area resulting in band dispersion changes. Apparently the tension reaches a maximum at an iron layer thickness of 1.35 nm, and a high effective hole mobility equal to 820  cm(2) V(-1) s(-1) was registered.