ellipsometrische

Ellipsometry is an optical technique used to determine the dielectric properties (complex refractive index or dielectric function) of a material. It is based on the principle that the polarization state of light changes upon reflection from a surface. This change is characterized by the ratio of the complex reflection coefficients for light polarized parallel and perpendicular to the plane of incidence, known as the ellipsometric ratio or psi (ψ) and delta (Δ).

Ellipsometry can be performed in various configurations, including null, rotating analyzer, and rotating polarizer. In null ellipsometry, the analyzer is adjusted to minimize the intensity of the reflected light, providing a direct measurement of the ellipsometric angles. Rotating analyzer and rotating polarizer ellipsometers, on the other hand, measure the intensity of the reflected light as a function of the analyzer or polarizer angle, respectively.

Ellipsometry is widely used in the characterization of thin films, surfaces, and interfaces. It can provide information about the thickness, composition, and optical properties of materials, making it a valuable tool in fields such as semiconductor manufacturing, materials science, and surface chemistry. Additionally, ellipsometry can be used to study the optical properties of materials in situ, under various environmental conditions, and at different wavelengths.

In recent years, advances in ellipsometry have led to the development of spectroscopic ellipsometry, which measures the ellipsometric angles as a function of wavelength. This technique provides a more comprehensive characterization of materials, allowing for the determination of their dispersion properties and the identification of different components in a mixture. Furthermore, the combination of ellipsometry with other techniques, such as X-ray photoelectron spectroscopy and atomic force microscopy, has enabled the development of multi-technique characterization platforms, which offer a more detailed understanding of material properties.