QUANTIZATION OF TERRACE WIDTHS ON VICINAL SI(111)

Scanning tunneling microscope (STM) and high resolution low-energy electron diffraction studies of slowly cooled Si(111) surfaces misoriented by 1.3-degrees towards the [112BAR] direction show the existence of a preferred displacement of the (7 x 7) reconstruction across single-layer steps. STM results show that this correlation is quite strong: it occurred in 42 of the 46 steps observed. The correlation leads to a quantization of the terrace widths to units of the (7 x 7) unit cell. Less extensive results on the 6-degrees misoriented surface suggest that the (7 x 7) reconstruction is also correlated across triple-layer steps.