Application of ellipsometry to surface films and film growth

Neal, W.E.J.

doi:10.1016/0376-4583(77)90001-2

Cited by 15 publications

(3 citation statements)

References 121 publications

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“…Spectroscopic ellipsometry is a technique that measures the change in the state of light polarization when light interacts with a surface. It is suitable for obtaining optical properties, such as the refractive index ( n ) and extinction coefficient ( k ) and for accessing the thickness of single- or multilayered thin films by using mathematical models. − The interest in using this technique has been increasing owing to its high precision and fast, noninvasive, and nondestructive measurements …”

Section: Resultsmentioning

confidence: 99%

Effect of pH on the Complex Coacervation and on the Formation of Layers of Sodium Alginate and PDADMAC

et al. 2020

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In this study, we investigated the thermodynamic features of a system based on oppositely charged polyelectrolytes, sodium alginate, and poly(diallyldimethylammonium chloride) (PDADMAC) at different pH values. Additionally, a comparison of the effects of the thermodynamic parameters on the growth of the layers based on the same polymers is presented. For this investigation, different techniques were combined to compare results from the association in solution and coassembled layers at the silicon surface. Dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) were used for studies in solution, and the layer-by-layer technique was employed for the preparation of the polymer layers. Ellipsometry and atomic force microscopy (AFM) were used to characterize the layer thickness growth as a function of the solution pH, and interferometric confocal microscopy was employed to analyze the topography and roughness of the films. The titration of both polyelectrolytes in two different sequences of additions confirmed the mechanism; it involved a two-step process that was monitored by varying the enthalpy, as determined by ITC experiments, and the structural evolution of the aggregates into coacervates, according to DLS. The primary process is aggregation to form polyelectrolyte complexes having a smaller hydrodynamic diameter, which abruptly transit toward a secondary process because of the formation of coacervate particles that have a larger hydrodynamic diameter. Independent of pH and the sequence of addition, for the first process, both directions are entropically driven. However, the binding enthalpy (ΔH b ) decreased with a decrease in the pH of the solution. The layers grown for the PDADMAC/sodium alginate system demonstrated pH sensitivity with either linear or exponential behavior, depending on the pH values of the polyelectrolyte solutions. The more endothermic process at pH 10 afforded layers with a smaller thickness and with linear growth according to the increase in the number of layers from 5 to 20. Decreases in the pH of the solution resulted in the layers growing exponentially; additionally, a decrease in the ΔH b of the association in the solution was observed. The layer thicknesses measured using ellipsometry and AFM data were in good agreement. Additionally, the influence of pH on the roughness and topography of the films was observed. Films from basic dipping solutions resulted in surfaces that were more homogeneous with less roughness; in contrast, films with more layers and those formed in a low-pH dipping solution were rougher and less homogeneous.

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Section: Resultsmentioning

confidence: 99%

Effect of pH on the Complex Coacervation and on the Formation of Layers of Sodium Alginate and PDADMAC

et al. 2020

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“…The reference positions of azimuths of the instrument were first determined (see Neal 1977a). With the compensator removed and using the wavelength for maximum sensitivity the polariser and analyser were rotated until an extinction position was obtained.…”

Section: Tests On Gold Samplesmentioning

confidence: 99%

An ellipsometer for student experiments

Neal

Petraitis

1981

Eur. J. Phys.

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Recent interest in the properties of surfaces in a variety of material based industries has led to the development of instruments. The author describe a relatively inexpensive manually operated ellipsometer for student use by adapting an optical spectrometer on which are mounted a polariser, compensator and analyser. The light sensitive detector was a phototransistor and DC amplification was obtained with an FET operational amplifier in an integrated circuit form. The instrument can be used with or without phase compensation for the analysis of elliptically polarised light in the reflected beam from a specimen mounted on the spectrometer table. Results are given for the optical constants of gold and aluminium over the wavelength range 545-804 nm and for hydroxide film growth up to 130 nm thickness on commercial aluminium exposed to saturated water vapour at 90 degrees C with a radiation wavelength of 804 nm. The angle of incidence on the instrument can be varied and this provides a useful facility to demonstrate the effect of the angle of incidence on sensitivity for surface film thickness measurement.

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“…3). After a vacuum measurement, the chamber is allowed to return to the ambient room pressure and temperature.…”

Section: Errors Associated With Ellipsometer Componentsmentioning

confidence: 99%

An Investigation of the Techniques of Ellipsometry, Internal Reflection Spectroscopy, and Moment Analysis to the Study of Films and Substrates

Palmer¹,

Williams²

1981

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Application of ellipsometry to surface films and film growth

Cited by 15 publications

References 121 publications

Effect of pH on the Complex Coacervation and on the Formation of Layers of Sodium Alginate and PDADMAC

Effect of pH on the Complex Coacervation and on the Formation of Layers of Sodium Alginate and PDADMAC

An ellipsometer for student experiments

An Investigation of the Techniques of Ellipsometry, Internal Reflection Spectroscopy, and Moment Analysis to the Study of Films and Substrates

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