In situ analysis of the room-temperature epitaxial growth of CeO2 ultrathin films on Si (111) by coaxial impact-collision ion scattering spectroscopy

The room-temperature epitaxial growth of CeO2 films on Si(111) substrates w as examined in situ by combined use of a coaxial impact-collision ion scatt ering spectroscopy (CAICISS) and the laser molecular beam epitaxy (laser MB E). It was found that the crystal quality of CeO2 ultrathin films (similar to3 nm thick) as-grown in UHV (similar to 10(-9) Torr) could be improved re markably by a few minutes of O-2 gas exposure (similar to 10(-5) Torr) at r oom temperature. A three-fold symmetry in the Ce signal intensity of azimut h rotational CAICISS spectra, which exhibited the type-B epitaxial growth ( [(1) over bar 10](CeO2)parallel to [1 (1) over bar0](Si)), was observed for the films thicker than about 1 nm. (C) 2001 American Institute of Physics.