In this paper, we investigated the optical and thermo-optical properties of a-SiN_x:H layers obtained using the PECVD technique. SiN_x:H layers with different refractive indices were obtained from silane and ammonia as precursor gases. Surface morphology and chemical composition studies were investigated using atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectrometry methods. Spectroscopic ellipsometry was used to determine the optical indexes, thicknesses and optical bandgap of the films. The main purpose was to identify the thermo-optical characteristics of layers with different refractive indexes. Thermo-optical studies were performed to determine the temperature hysteresis of optical parameters. These measurements showed that after annealing up to 300 °C and subsequent cooling, the value of optical parameters returned to the initial values.

This paper presents the results of investigations of optical scattering phenomena in porous silica films. SiO₂ films were prepared by the sol-gel method and deposited on polished silicon wafers by the dip-coating technique. Fabricated films were studied using integrating sphere reflectometry, spectroscopic ellipsometry, atomic force microscopy, scanning electron microscopy, and angular resolve scattering. The spectral characteristics of the refractive and extinction indices and scattering extinction coefficients are presented. Additionally, the depolarization of reflected beam from samples was measured. The tested films were characterized by a thickness of 500 to 900 nm, a porosity of 50%, and refractive indices of less than 1.24. The observed depolarization of light reflected from SiO₂ films resulted from surface and bulk scattering. This phenomenon resulted from the presence of surface and closed pores located in the bulk of SiO₂ film.

The aim of this work was the determination of the basic optical parameters and electronic structure of conjugated polymer films by two commonly used techniques—spectrophotometry and ellipsometry. Poly(3-hexylthiophene (P3HT) and poly(3-octylthiophene (P3OT) conductive polymers films deposited on a glass substrate by the spin-coating technique showed very comparable surface structures composed of grains of similar sizes and shapes. X-ray tests confirmed that the polythiophene layers are amorphous, which confirmed the correctness of the choice of the optical models used. Selected optical models (Lorentz, Tauc–Lorentz and Cody–Lorentz) have been applied in order to determine the thickness, and optical parameters such as refractive index and extinction coefficient, absolute absorption and electronic parameters (energy gap E_g, amplitude A and broadening B). Spectral absorption determined from spectrophotometric measurement is similar to the absorption spectrum obtained from the ellipsometry method with the application of oscillator models.

In this work, the results of ellipsometric studies of thin films of broadband oxides (ZnO, TiO₂, ZrO₂) and broadband oxides doped with Al₂O₃ (Al₂O₃–ZnO, Al₂O₃–TiO₂, Al₂O₃–ZrO₂) are presented. All layers have been produced using the atomic layer deposition method. Ellipsometric studies were performed in the wavelength range of 193–1690 nm. Sellmeier and Cauchy models were used to describe the optical properties of the tested layers. Dispersion dependencies of refractive indices were determined for thin layers of broadband oxides on silicon substrates, and then for layers of Al₂O₃ admixture. The EDX investigations enabled estimation of the composition of the alloys. The Bruggeman effective medium approximation (EMA) model was used to determine the theoretical dependencies of the dispersion refractive indices of the studied alloys. The refractive index values determined using the Bruggeman EMA model are in good agreement with the values determined from the ellipsometric measurements. The doping of thin layers of ZnO, ZrO₂ and TiO₂ with Al₂O₃ enables the creation of anti-reflective layers and filters with a specific refractive index.

In this paper we present results of ellipsometric studies of thin organic poly-3hexylthiophene–(P3HT) and poly-3octylthiophene (P3OT) films performed in temperature range 20–300 °C. The optical dispersion spectra of refractive and extinction indices of presented organic films was determined in wavelength range 190–1700 nm for temperatures within in a given range. Also thermo-ellipsometric investigations allowed to find temperature dependence on film thickness. The determination of thermal changes of thickness and refractive index allowed us to calculate thermo-optical coefficients (TOC) for P3HT and P3OT layers for many wavelengths in measured spectral range. The obtained values of thermo-optical coefficients of thin P3HT layers, determined from combined ellipsometric and spectro-photometric investigations, are negative in visible part of spectral range of the order of 10⁻⁴ [1/K] .