Ellipsometry analyzer angle

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. 

A variety of surface-sensitive spectroscopic and microscopic methods were critical in the investigation of these systems. In the work by Advincula et al, the composition, thickness, physical and thermal properties, and morphology of the tethered polymer brushes were carefully analyzed [72]. A variety of surface-sensitive techniques such as ellipsometry, contact angle measurements, AFM, quartz crystal microbalance (QCM), FT-IR grazing incidence... 

Ellipsometry, Table 1 Zone relations for a PCSA null ellipsometer. P is the polarizer angle, C is the compensator angle, and A is the analyzer angle... 

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. 

Fig. 4.2. The schematic experimental setup for reflection ellipsometry. The light from the laser source is guided through the polarizer (P) and PEM with its optical axis at an angle of 45° with respect to the direction of the polarization. The light beam is reflected from the lower side of the prism and is detected after passing through the analyzer, which is crossed with respect to the analyzer. DC, 1st and 2nd harmonic of the modulated light intensity are simultaneously measured, using the lock-in amplifier and computer for data acquisition. The prism has been used to eliminate parasite reflection from the air-glass interface. The x axis is parallel to the s polarization of light.

If measuring equipment for ORD and CD (Section 16.3.7.2) is combined with a reflection system, either ellipsometry at one wavelength or spectral ellipsometry can be carried out at defined angles (Fig, 23). In this apparatus, a rotating polarizer is used to produce rotating plane-polarized light. After reflection, an analyzer is used to meas-... 

The determinations of A and ij/ are made by adjusting the angles of the polarizer and analyzer alternately until the minimum (null) intensity is registered by the photodetector. This is the null method of ellipsometry. 

The angles P of the polarizer and A of the analyzer satisfying the above relations are called the null positions of the polarizer and analyzer, respectively, because the light reaching the detector of the ellipsometer is a minimum. The relations between the null instrument readings (A and P) and the ellipsometry parameters (A and i/f), Eqs. (5.41) and (5.42), are thus deduced by the use of the Poincare sphere. 

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