Analysis of the dielectric constants of the Ag2O film by spectroscopic ellipsometry and single-oscillator model

Ag2O film was prepared on glass substrate by direct current reactive magnetron sputtering under a careful control of the preparation parameters. The analysis of the dielectric constants of the Ag2O film related to the optical properties was conducted by spectroscopic ellipsometry (SE) and single-oscillator model. The dielectric constants were fitted in terms of general oscillator model (a model combined with three Tauc–Lorentz oscillator models) by using the measured SE data. Refractive-index dispersion data below the interband absorption edge of the Ag2O film were analyzed using a single oscillator fit of the form n2−1=EdE0/(E02−ℏ2ω2) proposed by Wemple and DiDomenico, where ℏω is the photon energy, E0 is the single oscillator energy, and Ed is the dispersion energy. The optical energy gap of approximately 2.32 eV was fitted by single oscillator model, which was in good agreement with that in terms of Tauc relation. The fitted dispersion energy Ed of approximately 20.28 eV determined the parameter β of approximately 0.32 by a simple empirical relationship Ed=βNcZaNe, which indicated that Ag2O film falls into covalent class. Additionally, the band gap parameter Ea and plasma frequency ℏωp fitted were 1.16 and 4.85 eV, respectively.