Major stable surface of silicon: Si(20 4 23)

Clean and well-annealed Si(515), (516), and (405) surfaces have been investigated by means of scanning tunnel microscope (STM) and low-energy electron diffraction and it turns out that these surfaces are unstable while Si(20 4 23) is stable, because the former three all consist of (20 4 23) facets. On the basis of the high-resolution dual-bias STM images of the (formula presented) surface, a detailed structural model of the surface has been proposed for further investigation. As the unit cell of the Si(20 4 23) surface has its own structure rather than consisting of nanofacets of other stable surface(s) the surface is identified, by definition, as a major stable surface (or MAJOR). Interestingly, among all MAJOR’s of silicon that have been found so far (20 4 23) is the only one that silicon does not share with germanium.