The structure of clean and SiGe-covered Si(110) surfaces

By means of scanning tunnelling microscopy (STM) the structure of clean and SiGe-covered Si(110) surfaces was studied. On the clean Si(110) surface particular attention was devoted to the structure and growth mode of (110) terraces which were found to be built up of 2.5 nm broad terraces with an alternating height of one monolayer. A subsequent Si layer, however, gives rise to a phase shift of the terrace structure. The structure of SiGe-covered surfaces was studied by STM and Auger electron spectroscopy (AES). The Ge-rich alloy also formed a terrace structure with a slightly changing width of around 1.9 nm, which is supposed to be caused by the statistical fluctuation of the Ge concentration. At small Ge concentrations a structure of well-aligned terraces, about 3.9 nm broad, was observed.