ATOMIC ARRANGEMENTS OF 16X2 AND (17,15,1)-2X1 STRUCTURES ON A SI(110) SURFACE

The 16X2 structure and the (17,15,1) 2X1 structure have been found on a Si(110) surface. Scanning-tunneling-microscope (STM) observations showed that the 16X2 structure was similar to the (17,15,1) 2X1 structure and both of them had a common structural unit. In the top view, the 16X2 structure is identical to the (17,15,1) 2X1 structure, but in the side view, the 16X2 structure is on the (110) plane and the (17,15,1) 2X1 structure on the (17,15,1) vicinal plane. A. unit cell of the (17,15,1) 2X1 structure is identical to the common unit cell and that of the 16X2 structure is represented by a pair of the upper and lower terraces formed by the common unit cell. A rumpling model for the 16X2 structure and the (17,15,1) 2X1 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.