Magnesium induced superstructural changes in high index Si (5 5 12) surface: formation of quasi one dimensional structures.

This is the first report of the initial formation of Mg/Mg2Si/Si interface at room temperature on high index Si (5 5 12) surface. The work describes the initial Mg2Si formation on the silicon surface, which forms a silicide layer after a critical coverage, and then metallic magnesium forms on top of the Mg2Si layers. The studies have been performed in situ in ultra high vacuum conditions (5 x 10(-11) Torr) and analyzed by surface sensitive techniques like Auger electron spectroscopy, electron energy loss spectroscopy, and low energy electron diffraction. The Auger uptake curve obtained by AES, shows the layered growth of Mg while the LEED and EELS shows the formation of surface phases, which are identified as the quasi 1D structure, with different electronic natures indicated by EELS studies. The growth process occurs in the following way that firstly the adsorption of Mg reconstructs the Si (5 5 12)-2 x 1 surface and forms two stable phases-Si (337) and Si (113) below the coverage of 1 ML, while there is Mg2Si formation at the coverage of 1 ML, further increase in the coverage of magnesium results in the metallic magnesium on top of the Mg2Si layer. Thus, with the Mg adsorption at RT not only the Si (5 5 12)-2 x 1 surface is reconstructed to give the stable phases but it also demonstrates the formation of Mg2Si at RT, which is the interfacial layer in between metallic Mg and Si.