Spectroscopic-ellipsometry study of the optical properties of ZnO nanoparticle thin films.

We described optical properties of zinc oxide (ZnO) nanoparticles determined by spectroscopic ellipsometry analysis from ex situ spectroscopic ellipsometry (ex situ SE) measurements made on nanocrystalline thin films over a spectral range of 0.734 to 4.00 eV. We determined the complex refractive index function, n ~ (ω) = n (ω) + i κ (ω) , by fitting a layered parametric model to the ellipsometric measurements. We collected SE measurements at an incidence angle of 70°. We also determined absorption coefficient spectra using extinction coefficient, κ and wavelength, λ. The direct optical bandgap of the films was obtained as 3.2 eV using the ellipsometric method. [ABSTRACT FROM AUTHOR]