Ellipsometry applications

No attempt has been made to survey comprehensively the wide and diverse field of ellipsometry applications, as several such reviews are available. A most important area which has hardly been mentioned, for example, is that of corrosion and a review of the field up to 1972 is provided by Kruger [26]. Another useful review covers a wider range of the literature up to about 1978 [27]. For semiconductor applications, with emphasis on later developments in the theory of multilayer structures, two reviews by Aspnes can be recommended [22, 28]. The proceedings of the international conferences on ellipsometry are an excellent source of information on developments in instrumentation, theory, and applications in all areas of surface physics and chemistry [29-33],... 

Snyder P.G., Rost M.C., George H., Woollam J.A., Alterovitz S.A. Variable angle of incidence spectroscopic ellipsometry application to GaAs-Al cGai c As multiple heterostructures. J. Appl. Phys. 1986 60 3293-3302... 

A newer and perhaps more useful application of ellipsometry to Langmuir films is their lateral characterization via ellipsometric microscopy [146], A simple modification of the nuU ellipsometer allows one to image features down to 10-/im resolution. Working with a fixed polarizer and analyzer, some domains are at extinction while others are not and appear bright. This approach requires no fluorescent label and can be applied to systems on reflective supports. 

Early work in ellipsometry focused on improving the technique, whereas attention now emphasizes applications to materials analysis. New uses continue to be found however, ellipsometry traditionally has been used to determine film thicknesses (in the rang 1-1000 nm), as well as optical constants. " Common systems are oxide and nitride films on silicon v ers, dielectric films deposited on optical sur ces, and multilayer semiconductor strucmres. 

Infrared ellipsometry is typically performed in the mid-infrared range of 400 to 5000 cm , but also in the near- and far-infrared. The resonances of molecular vibrations or phonons in the solid state generate typical features in the tanT and A spectra in the form of relative minima or maxima and dispersion-like structures. For the isotropic bulk calculation of optical constants - refractive index n and extinction coefficient k - is straightforward. For all other applications (thin films and anisotropic materials) iteration procedures are used. In ellipsometry only angles are measured. The results are also absolute values, obtained without the use of a standard. 

Gottesfeld, S., Y.-T. Kim, and A. Redondo, Recent applications of ellipsometry and spec-troellipsometry in electrochemical systems, in Physical Electrochemistry, I. Rnbenstein, Ed., Marcel Dekker, New York, 1995, p. 393. 

Until quite recently the very initial stages of metal deposition were difficult to characterize in detail by structure- and morphology-sensitive techniques. As a consequence and for practical purposes - multilayers were more useful for applications than monolayers - the main interest was focussed onto thick deposits. Optical and electron microscopy, ellipsometry and specular or diffuse reflectance spectroscopy were the classic tools, by which the emerging shape of the deposit was monitored [4-7],... 

The heart of the polarization-modulated nephelometer is a photoelastic modulator, developed by Kemp (1969) and by Jasperson and Schnatterly (1969). The latter used their instrument for ellipsometry of light reflected by solid surfaces (the application described here could be considered as ellipsometry of scattered light). Kemp first used the modulation technique in laboratory studies but soon found a fertile field of application in astrophysics the modulator, coupled with a telescope, allowed circular polarization from astronomical objects to be detected at much lower levels than previously possible. 

A number of special optical techniques such as the study of second harmonic generation by irradiation of non-centrosymmetric systems by high intensity laser light will be discussed in relation to particular materials and problems. However, one optical technique having a general applicability, namely ellipsometry, must be discussed here. It is one of the best techniques available to determine the thickness of a thin organic film. Such determinations are important as they allow one to have an independent check on the number of layers deposited, given that the thickness of one layer has been determined by X-ray diffraction. 

DePalma and Tillman investigated self-assembled monolayer films from three silanes, tridecafluorooctyltrichlorosilane, undecyltrichlorosilane, and octadecyl-trichlorosilane, on silicon, a popular model substrate for such studies with great relevance to potential semiconductor coating applications. They characterized the films by ellipsometry and contact angle measurements (data for trideca-fluorooctyltrichlorosilane are included in Table 1), but more usefully from an applicational viewpoint, they carried out friction and wear measurements with a pin-on-disk device where the silicon wafer substrate, coated with monolayer, is moved under a spherical glass slider. Optical microscopy was used to assess wear. Table 2 summarizes DePalma and Tillman s data and their comparison with the classical self-assembled monolayer friction studies of Levine and Zisman [18]. 

In research on the mechanisms gouverning the modification reactions, the thin silica layers allow the application of various surface analytical techniques, which are of no use for analysis inside porous systems. Reaction mechanisms are simplified by the elimination of porosity and may be studied by direct surface techniques such as ellipsometry, as well as microscopic techniques such as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).59... 

H. Fujiwara, Spectroscopic Ellipsometry Principles and Applications (John Wiley Sons Ltd, Chichester, 2007)... 

Adsorption of polymers on inorganic substrates has been subject of numerous investigations because of the simple procedure for application [12-15], In this work the influence of the amino group content and pH of the PVFA-co-PVAm solution on the amount of adsorbed polymer on various metal surfaces has been studied. Metal substrate samples of different size and shape (particles, sheets) have been used which limits the application of special surface sensitive methods such as ellipsometry. 

Judicious application of micropolarization techniques [81], as well as ellipsometry [82] and XRD [83], enabled analysis of the multilayer structure of the surface films formed on lithium in solutions. 

Our approach to this problem involves a detailed mechanistic study of model systems, in order to identify the (electro)chemical parameters and the physicochemical processes of importance. This approach takes advantage of one of the major developments in electrochemical science over the last two decades, namely the simultaneous application of /ton-electrochemical techniques to study interfaces maintained under electrochemical control [3-5]. In general terms, spectroscopic methods have provided insight into the detailed structure at a variety of levels, from atomic to morphological, of surface-bound films. Other in situ methods, such as ellipsometry [6], neutron reflectivity [7] and the electrochemical quartz crystal microbalance (EQCM) [8-10], have provided insight into the overall penetration of mobile species (ions, solvent and other small molecules) into polymer films, along with spatial distributions of these mobile species and of the polymer itself. Of these techniques, the one upon which we rely directly here is the EQCM, whose operation and capability we now briefly review. 

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