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Of late there is great interest in the adsorption studies on the highly trenched and faceted high index Si (5 5 12) surface which can act as a template for the formation of quasi-one-dimensional nanowires. This work is the first report on the submonolayer adsorption of magnesium on the Si (5 5 12) surface, at room and higher temperatures and its residual thermal desorption. The growth and interface formation studies have been performed in UHV by in-situ surface sensitive probes such as Auger electron spectroscopy (AES), Low energy electron diffraction (LEED) and Electron energy loss spectroscopy (EELS). The Auger uptake curve at room temperature shows the layered growth of Mg and LEED and EELS reveal the formation of low dimensional surface phases, with different electronic properties. The LEED studies show that the large unit cell of the clean Si (5 5 12)-2x1 surface is observed to reduce to smaller units such as (1 1 3) and (3 3 7) with increased Mg coverage. The RT adsorption of a critical Mg coverage results in the formation of magnesium silicide (Mg2Si). The residual thermal desorption of this Mg/Si (5 5 12) interface shows the formation of several surface superstructures, including quasi one-dimensional nanowire formation, and its dependence on Mg coverage and temperature (substrate and annealing). The EELS spectra observed during the RT adsorption and residual thermal desorption reveal the characteristic features related to the electronic structural changes that occur during the surface structural phase manifestations. The superstructural phases formed on the Si (5 5 12)-2x1 surface are also compared with the geometrical and electronic structures of the Mg induced superstructural phases formed on the low index surfaces like Si (111)-7x7 and Si (001)-2x1 surface. |