INITIAL-STAGES OF EPITAXIAL-GROWTH OF Y-STABILIZED ZRO2 THIN-FILMS ONA-SIOX SI(001) SUBSTRATES/

The initial stages of crystallization and growth of epitaxial Y-stabil ized ZrO2 (YSZ) thin films on Si (001) substrates covered with amorpho us native oxide were investigated by transmission electron microscopy (TEM) and reflection high-energy electron diffraction (RHEED). The YSZ crystallizes by solid-phase epitaxy with an initial thickness of 1 nm . The crystallization is initially incomplete, yielding both epitaxial and disordered regions of the YSZ film. In situ RHEED measurements sh owed the lattice parameter of the YSZ gradually decreased during growt h, reaching the bulk value at a film thickness of 5-7 nm. For a larger thickness, the film is fully elastically relaxed. TEM revealed misfit dislocations at the YSZ/Si interface. The average spacing between mis fit dislocations with Burgers vector b = 1/2 [110] was measured as 8.3 nm, showing epitaxial misfit strain to be fully accommodated by misfi t dislocations. Thermal strain introduced during cooldown from the dep osition temperature is fully elastically accommodated. For YSZ thickne sses below 7 nm, the thickness of the regrown layer of silicon oxide a t the YSZ/Si interface is 0-0.5 nm.