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

Abstract

Electrical and optical properties of thin iron layers grown at room temperature on the epitaxial silicide Si(111)-(2 × 2)–Fe phaseand on an Si(111)7 × 7 surface were investigated using in situ Hall effect registration, atomic forcemicroscopy, and optical spectroscopy. It was established that Si(111)-(2 × 2)–Fe phase has semiconducting properties with a 0.99 eV effective band gapand acts as a diffusion barrier for the deposited iron atoms, preventingintermixing with the substrate at room temperature. Peculiarities in theoptical 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 conservationof 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 arearesulting in band dispersion changes. Apparently the tension reaches a maximum at aniron layer thickness of 1.35 nm, and a high effective hole mobility equal to 820 cm2 V−1 s−1 was registered.