RBBR SI(111) INTERFACE STUDIED BY THE X-RAY STANDING-WAVE METHOD/

The RbBr/Si(111) interface has been studied by using the X-ray standin g wave technique in order to determine the adsorption distances of Br and Rb atoms to the substrate [111] planes. The adsorption distances p rovide information both on the adsorption geometry and on the nature o f the element directly bonded to the substrate (i.e. the interface ato mic structure). By varying the deposition order and the coverage ratio of Br to Rb, it has been deduced that the element present with a high er coverage is directly bonded to the substrate. The adsorption distan ce for this element is very close to the distance determined in absenc e of the second element. After a mild annealing, no significant change s in the overlayer structure were observed, but some improvement of it s ordering. Annealing to higher temperatures resulted in total desorpt ion of the element of smaller initial coverage.