Five Ge films with thickness 250, 20, 10, 5 and 1 nm were sputter deposited on fuzed quartz substrates and annealed at 700 degree(s)C for 1 hour in vacuum. Optical properties of those films were measured using a spectroellipsometer and spectrophotometers. The thickest film was used to determine annealing condition and it can be regarded as the bulk. Dielectric constants were analyzed by the use of model dielectric function developed by Adachi (Jpn. J. Appl. Phys. 32 (1993) 3168). Thickness dependence was clearly observed. The thinnest Ge film was alternately deposited with SiO₂ layer. Thickness of the SiO₂ layer was changed accordingly 1, 2 and 5 nm to change the volume fraction of Ge. Comparing extinction spectra between measured and calculated using multilayer model as well as effective medium approximation, we found that optical properties in very thin Ge layer is quite different from that of the bulk, suggesting appearance of the quantum size effects.

Date Published: 26 October 1994
PDF: 6 pages
Proc. SPIE 2364, Second International Conference on Thin Film Physics and Applications, (26 October 1994); doi: 10.1117/12.190779

Published in SPIE Proceedings Vol. 2364:
Second International Conference on Thin Film Physics and Applications
Shixun Zhou; Yongling Wang; Yi-Xin Chen; Shuzheng Mao, Editor(s)