A study was made of clean and well-annealed (113) surfaces by using scanning tunnelling microscopic and low-energy electron diffraction techniques. It was found that the surface consisted of very large 3x1 reconstructed domains, with many small 3x2 antiphase domains scattered among them. The use of scanning tunnelling microscopy revealed that neither the 3x1 nor the 3x1 reconstruction had a mirror plane. This ruled out all of the proposed (113)Si-derived models for the present surface. A model without a mirror plane was proposed here for the 3x1 reconstruction. This model involved a re-bonded atom and an adatom, as well as 5 dangling bonds, in each unit cell. A model was also proposed for the 3x2 reconstruction. This was different from, but similar to, an interstitialcy model which had recently been proposed for the Si(113)-3x2 surface. The unit cell of the present 3x2 model consisted of 2 unit cells of the present 3x1 model, and a sub-surface interstitial in one of the 3x1 unit cells. Both of the proposed models were consistent with the observed scanning tunnelling microscopic images.

Z.Gai, H.Ji, B.Gao, R.G.Zhao, W.S.Yang: Physical Review B, 1996, 54[12], 8593-9