Precise determination of optical properties of pentacene thin films grown on various substrates: Gauss-Lorentz model with effective medium approach

Abstract

Spectroscopic ellipsometry measurements are performed on thin pentacene films grown on glass, SiO(2), and n-Si substrates. The Gauss-Lorentz oscillator model is shown to be effective in modeling the pi-pi (au) transitions found in organic compounds. The effective medium approximation that considers the surface roughness of the films, which can be significant in case of pentacene, is also shown to be a key factor in precisely determining their dielectric functions. The proposed method reveals that there are some quantitative differences in the optical properties of the pentacene films prepared on different substrates.