The atomic structure of the monohydride Si(001)-(2 x 1)-H reconstruction was investigated by surface X-ray diffraction. Atomic relaxations down to the eighth layer were determined. The bond length of the hydrogenated silicon dimers was found to be 2.47Å, which was longer than the dimer bond of the clean (2 x 1)-reconstructed Si(001) surface and also 5% longer than the bulk bond length of 2.35Å. The differences to the (2 x 1) structure of the clean surface were discussed in terms of the elimination of the weak π-bond character of the dimer bond by the addition of hydrogen.

Structure Determination of the Si(001)-(2 x 1)-H Reconstruction by Surface X-Ray Diffraction -Weakening of the Dimer Bond by the Addition of Hydrogen. E.M.Lauridsen, J.Baker, M.Nielsen, R.Feidenhans, G.Falkenberg, O.Bunk, J.H.Zeysing, R.L.Johnson: Surface Science, 2000, 453[1-3], 18-24