SURFACE CRYSTALLOGRAPHY OF YSI2-X FILMS EPITAXIALLY GROWN ON SI(111) - AN X-RAY PHOTOELECTRON DIFFRACTION STUDY

The surface crystallography of epitaxially grown YSi2-x (x=0.3 and x=0) films on Si(111) has been investigated using x-ray photoelectron diffraction. For the YSi1.7 films, vacancies form an ordered 3 × 3 R30°superlattice within each Si plane. These vacancies are filled for YSi2. The analysis reveals that their surfaces are Si terminated with a displacement upward (0.8 AI) of one Si atom out of two so that they exhibit the same geometry as a 1×1 Si(111) surface. © 1990 The American Physical Society.