LEED IV CURVE ANALYSIS FOR THE STRUCTURE OF IRON FILMS ON SI(111) SURFACES

Iron films deposited on Si(111)7×7 surfaces grow layer-by-layer and the structure of iron films of more than half a monolayer ( 1 2 ML) average thickness changes from a 1×1 to a 2×2 superstructure after annealing above 400°C. LEED I-V curves of several beams have been measured, and for a film of 1 ML average thickness, experimental curves are compared with curves obtained by dynamical calculations. Consequently, it is most probable for the 1×1 structure that iron atoms sit in 3-fold hollow sites on a Si substrate which is missing the topmost plane. © 1989.