A method has been developed for analysis of a series of ellipsometric data taken in situ during deposition. With this method the optical constants n and k and thickness d of growing ion-beam-sputtered films of C, Si, Ni, Nb, Mo, Ru, Rh, Pd, Ag, W, Re, and Au have been determined as a function of deposition time t. The minimum critical thickness dc needed for a film to become optically isotropic has been determined from the n, k, d-versus-t curves. Anomalous behavior of these curves appears in the region d ≲ dc resulting from a breakdown of the isotropic film model employed. This is shown, by transmission electron micrographs, to have a correlation with a transition region from island/anisotropic to continuous/isotropic.
© 1992 Optical Society of America
Original Manuscript: January 8, 1991
Published: April 1, 1992
Masaki Yamamoto and Takeshi Namioka, "In situ ellipsometric study of optical properties of ultrathin films," Appl. Opt. 31, 1612-1621 (1992)