Formation of ytterbium silicide on (111) and (001)Si by solid-state reactions

The formation of ytterbium silicide on (1 1 1) and (0 0 1)Si substrates was studied by both conventional transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). Amorphous interlayers were formed between Yb thin films and (1 1 1)Si substrates during room-temperature deposition. The interlayer grew thicker at elevated temperatures. Epitaxial YbSi2-x films were formed after annealing at 300 degreesC for 30 min. The films contain serious lattice distortion and a vacancy ordering superlattice structure. The vacancy ordering superlattice structure was transformed into an out-of-step structure after higher temperature annealing. For the films deposited on (0 0 1)Si, polycrystalline rather than epitaxial silicide was formed after high-temperature annealing. (C) 2001 Elsevier Science Ltd. All rights reserved.