OPTICAL-PROPERTIES OF EPITAXIAL COSI2 ON SI FROM 0.062 TO 22.3 EV

The optical constants of epitaxial CoSi2 filMS On Si from 0.062 to 22.3 eV have been determined by ellipsometry and reflectance measurements. The energy dependencies of the dielectric functions show Drude behavior at energies lower than approximately 0.2 eV with Drude parameters homega(p)BAR=(5.8+/-0.2) eV and hBAR/tau=(0.09+/-0.02) eV. The energy-loss function, calculated from the optical constants, shows two peaks that correspond to the screened plasma oscillation and volume plasma oscillation of all valence electrons. Using the measured optical constants, a composite thin film of epitaxial CoSi2 particles embedded in Si is shown to have the absorptance peak due to a surface-plasmon resonance in the CoSi2 particles. The peak shifts to higher energy as the ellipsoidal particles become more elongated, in good agreement with recent observations by Fathauer et al. [Phys. Rev. B 44, 1345 (1991)].