RECONSTRUCTION OF A CS-ADSORBED SI(111) 7X7 SURFACE

We have studied the (3 X 1) reconstruction of a Cs-adsorbed Si(111) 7X 7 surface using reflection high energy electron diffraction and X-ray photoelectron spectroscopy. The (3 x 1) surface consists of a well-ord ered adlayer with a (3 X 1) structure of Cs atoms on the Si(111) surfa ce, and this is consistent with the results of scanning tunneling micr oscopy studies of Ag and Li-induced Si(111) 3 X 1 structures. It was o bserved that the (3 x 1) structure was transformed to the (6 X 1) stru cture by enlarging the (3 X 1) domain size and that the coverage of th e Si(111) 3 X 1-Cs surface is 2/3 ML.