Ellipsometryrelated

Ellipsometry-related refers to techniques, instrumentation, and analysis connected with ellipsometry, an optical method for characterizing thin films. In a typical ellipsometry measurement, polarized light is reflected from a sample and the change in polarization is measured to determine film thickness and optical constants.

Two primary parameters, psi and Delta, describe the amplitude ratio and phase difference between p- and s-polarized reflected light, related to the complex reflectance ratio rho = rp/rs = tan(psi) e^{i Delta}. Spectroscopic ellipsometry extends this across wavelengths to extract dispersion information for the film and substrate.

Common configurations include rotating-polarizer ellipsometers, rotating-compensator setups, phase-modulated instruments, and Mueller-matrix ellipsometry for full polarization characterization. Imaging ellipsometry and spectroscopic ellipsometry are used for spatially varying samples or wide spectral ranges, respectively. These systems are used to probe very thin films as well as layered structures with high precision.

Data analysis uses optical models of multilayer stacks, employing Fresnel equations to simulate psi and Delta; parameters like layer thickness, refractive index n and extinction coefficient k, surface or interface roughness, and anisotropy are adjusted to fit measurements. Arriving at a unique solution often requires a physically reasonable model and, sometimes, supplementary data or constraints to reduce ambiguity.

Applications span semiconductor device fabrication, metal oxide coatings, polymer and organic films, sensors, and biological interfaces. Ellipsometry is highly sensitive to sub-nanometer thickness changes and can monitor in situ growth or chemical reactions during film formation.

Limitations include model ambiguity, parameter correlations, and limited sensitivity to very rough or diffuse surfaces. Accurate results depend on known substrate properties, well-controlled instrumentation, and thoughtful experimental design.

Ellipsometry-related topics also include porosimetry, Mueller-matrix analysis, and data interpretation methods used to characterize anisotropy and optical dispersion.