The 16×2 structure and the (17,15,1) 2×1 structure have been found on a Si(110) surface. Scanning-tunneling-microscope (STM) observations showed that the 16×2 structure was similar to the (17,15,1) 2×1 structure and both of them had a common structural unit. In the top view, the 16×2 structure is identical to the (17,15,1) 2×1 structure, but in the side view, the 16×2 structure is on the (110) plane and the (17,15,1) 2×1 structure on the (17,15,1) vicinal plane. A unit cell of the (17,15,1) 2×1 structure is identical to the common unit cell and that of the 16×2 structure is represented by a pair of the upper and lower terraces formed by the common unit cell. A rumpling model for the 16×2 structure and the (17,15,1) 2×1 structure is proposed on the basis of STM and ultraviolet-photoelectron-spectroscopy results, where Si atoms are displaced in the direction normal to the (110) surface and the displacement oscillates along the [110] direction. The corrugation in the rumpling is 0.5 nm.

• Received 22 February 1994

DOI:https://doi.org/10.1103/PhysRevB.50.8534