Ellipsometry polarized light

R.M. Azzam and N.M. Bashara, Ellipsometry and Polarized Light, New York North Holland, 1977. 

In ellipsometry monochromatic light such as from a He-Ne laser, is passed through a polarizer, rotated by passing through a compensator before it impinges on the interface to be studied [142]. The reflected beam will be elliptically polarized and is measured by a polarization analyzer. In null ellipsometry, the polarizer, compensator, and analyzer are rotated to produce maximum extinction. The phase shift between the parallel and perpendicular components A and the ratio of the amplitudes of these components, tan are related to the polarizer and analyzer angles p and a, respectively. The changes in A and when a film is present can be related in an implicit form to the complex index of refraction and thickness of the film. 

As discussed above, the reflection of linearly polarized light from a surface generally produces elliptically polarized light, because the parallel and perpendicular components are reflected with different efficiencies and different phase shifts. These changes in intensity and phase angle can be analyzed to characterize the reflecting system. This approach is called ellipsometry. 

In a typical ellipsometry experiment a sample is irradiated with polarized light, which subsequently is reflected from the sample surface and detected after passing an analyzer. The ratio p of complex reflectances for perpendicularly (s) and parallelly (p) polarized light usually is represented as follows ... 

Azzam R.M.A. and Bahara N.M., Ellipsometry and polarized light, North Holland, Amsterdam 1988. 

Spectroscopic Ellipsometry Porosimetry (EP). In general, ellip-sometry takes advantage of the change of polarization of a polarized light beam after reflection from a surface. From the parameters (T and A), obtained... 

Figure 7.25 Set-up for ellipsometry microscopy. Incident linearly polarized light reflects on the surface and becomes eiliptically polarized. The quarter wave plate converts the polarization from elliptical to linear. The analyzer is placed such that it extinguishes all light. If the reflection properties change because a gas is adsorbed, the polarization does not match the setting of the analyzer and light passes through it. Appropriate lenses project an image of the surface onto the CCD camera (adapted from Rotermund [72]).

Wasserman [186] has described the use of both low-angle X-ray reflectivity and ellipsometry for the determination of thickness of Cio-Cig SAMs prepared on surface silanol groups of silicon plates. Ellipsometry is based on the reflection of polarized light from a sample and depends on the sample s thickness and refractive index. X-ray reflectivity measures the intensity of X-rays reflected from a surface (or interference pattern) that is characteristic of the distance between interfaces. The thickness of the SAMs was consistent with fully extended alkyl chains with all-trans conformations and excellent agreement was observed between the two methods. 

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. 

Azzam, R. M. A. Bashara, N. M. "Ellipsometry and Polarized Light", North-Holland, Amsterdam, 1977. 

Ellipsometry Thickness, density, defect structure, interface width Monochromatic polarized light Polarization state of polarized light — Fraction of monolayer... 

The main experimental technique applied in this chapter is SE. Several textbooks were written on SE [73,114-118], Therefore, only some basic concepts are described. SE examines the relative phase change of a polarized light beam upon reflection (or transmission) at a sample surface. In Fig. 3.4 the setup of an ellipsometry experiment is shown. Upon model analysis of the experimental data, the DFs and thicknesses of the sample constituents can be extracted. Two different experimental approaches have to be distinguished, standard and generalized ellipsometry. 

R.M.A. Azzam, N.M. Bashara Ellipsometry and Polarized Light (North-Holland, Amsterdam, 1977) E. Echt Optics (Addison-Wesley, Reading, 1990) M. Born, M. Wolf Principles of Optics (Pergamon, Oxford, 1970)... 

R.M.A. Azzam, N.M. Bashara Ellipsometry and Polarized Light (North-Holland, Amsterdam 1977)... 

Ellipsometry measures the orientation of polarized light undergoing oblique reflection from a sample surface. Linearly polarized light, when reflected from a surface, will become elliptically polarized, because of presence of the thin layer of the boundary surface between two media. Dependence between optical constants of a layer and parameters of elliptically polarized light can be found on basis of the Fresnel formulas described above. 

Ellipsometry measures the relative attenuation and phase shift of polarized light reflected from a polymer-coated surface. The Drude equations (Drude, 1889a,b, 1890 Stromberg et ai, 1963 McCrackin and Colson, 1964) relate the attenuation and phase shift to the average refractive index and thickness tel of an equivalent homogeneous film. Interpretation of fel in terms of the actual refractive index distribution or the polymer distribution [Pg.189]

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