Dielectric function of V2O5 nanocrystalline films by spectroscopic ellipsometry: Characterization of microstructure

Spectroscopic ellipsometry over the photon energy 1.5-5.0 eV is used to der ive the dielectric function of V2O5 nanocrystalline films deposited by plas ma-enhanced chemical vapor deposition. The dispersion in the optical respon se is described by a combination of Lorentzian oscillators. The results are obtained from a microstructure-dependent model, which considers the anisot ropy of the V2O5 crystallites into the bulk film, as well as the presence o f interface and surface roughness layers. The variation of the V2O5 thin-fi lm dielectric function upon film crystallinity, going from pure nanocrystal line to amorphous material, is also investigated. (C) 2000 American Institu te of Physics. [S0003-6951(00)04034-1].