The evolution of vacancy ordering structures in epitaxial YbSi2–x thin films on (111) or (001)Si was studied by means of transmission electron microscopy. Epitaxial thin silicide films were grown onto Si by room-temperature deposition, with subsequent thermal annealing, or by deposition at high temperatures. Epitaxial YbSi2–x was found to form in annealed (300C, 0.5h) samples, and the appearance of additional diffraction spots was attributed to the formation of an ordered vacancy superstructure in the epitaxial YbSi2–x thin films. In other samples, splitting or streaking of extra diffraction spots was attributed to the formation of out-of-step structures. The variation in out-of-step structures with annealing temperature was related to a change, in the vacancy concentration, that made compressive stresses in the Si sub-lattice relax. By studying plan-view and cross-sectional transmission electron microscopy samples, in conjunction with simulated diffraction patterns, the 3-dimensional structures of vacancy ordering were determined.

Evolution of Vacancy Ordering Structures in Epitaxial YbSi2–x Thin Films on (111) and (001) Si. K.S.Chi, W.C.Tsai, L.J.Chen: Journal of Applied Physics, 2003, 93[1], 153-8