The formation of [formula omitted] interface at room and high temperatures

Abstract

The formation of a Mn Si(111) interface is studied by depositing submonolayer to several monolayer coverages θ of Mn at controlled rates and at different substrate and annealing temperatures. The observation of various surface phase formations, their transitions, and their dependence on deposition parameters are probed by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and electron energy loss spectroscopy (ELS). Deposition of Mn at very low rates (0.15 ML min −1) resulted in the formation of epitaxial structures even at room temperature (RT). It is observed for the first time that up to 1 ML, the low rate of arrival (deposition rate < 0.3 ML min −1) of Mn atoms at the Si(111) surface facilitates the growth of a Mn Si(111)-7 × 7 surface phase. Mn atoms arriving thereafter accumulate in the layer-by-layer (Frank-van der Merwe) mode resulting in the 1 × 1 epitaxial growth of Mn at least up to 2–3 ML at RT. Annealing at 350°C of the RT deposited Mn (1 < θ < 2 ML) results in a very sharp 1 × 1 phase as seen by LEED. However, annealing the RT deposited (> 3 ML) Mn Si(111) system results in a sharp √3 × √3 phase, which corresponds to the formation of manganese silicide as observed by ELS. It is found that using the 1 × 1 surface phase as a template results in high quality epitaxial √3 × √3 silicide formation. Deposition at low rates onto heated (350°C) Si(111) leads to Si(111)Mn 7 × 7 surface phase with the excess adatoms forming islands on the surface (Stranski-Krastanov mode).