Ellipsometry measurements

Dielectric constants of metals, semiconductors and insulators can be detennined from ellipsometry measurements [38, 39]. Since the dielectric constant can vary depending on the way in which a fihn is grown, the measurement of accurate film thicknesses relies on having accurate values of the dielectric constant. One connnon procedure for detennining dielectric constants is by using a Kramers-Kronig analysis of spectroscopic reflectance data [39]. This method suffers from the series-tennination error as well as the difficulty of making corrections for the presence of overlayer contaminants. The ellipsometry method is for the most part free of both these sources of error and thus yields the most accurate values to date [39]. 

Ellipsometry measurements can provide infomiation about the thickness, microroughness and dielectric ftinction of thin films. It can also provide infomiation on the depth profile of multilayer stmctiires non-destmctively, including the thickness, the composition and the degree of crystallinity of each layer [39]. The measurement of the various components of a complex multilayered film is illustrated m figure Bl.26.17 [40]. 

Ellipsometry measurement of the characteristics of polarised light after reflection from a surface. 

This research was supported by the NSF-MRL program through the Materials Research Center of Northwestern University (Grant DMR-8821571) and by the Air Force Office of Scientific Research (Contracts 86-0105 and 90-0071). We thank Mr. T. G. Zhang for helpful discussions and Drs. D. Lam and J. Parker of Argonne National Laboratory for assistance with the ellipsometry measurements. 

Another interesting and different type of catalysis is involved in the catalyzed reconstruction of an indium oxide overlayer on indium. This study was alluded to earlier in the discussion of acetate ion species formed on indium oxide by chemisorption from several torr of acetic acid gas. At low partial pressures of acetic acid (<< 0.1 torr) the reversible adsorption of acetic acid catalyzes the reconstruction of a thin ( 10-15A), porous indium oxide overlayer to a defect-free (no pin holes) film as judged by pinhole sensitive tunnel junction measurements. Some clues as to the mechanism were obtained from IR plus Auger and electron loss spectroscopy as well as ellipsometry measurements. The overall process is shown in Fig. 8. This is an example where processes in the substrate themselves can be usefully catalyzed. 

Values are mean values with the standard deviation shown in parentheses n=7 in each case, a ESCA measurements on silicon substrates, b Sessile drop measurements on glass slides, c Ellipsometry measurements on silicon substrates, d First receding contact angle. 

The adsorption kinetics from time resolved ellipsometry measurements showed two regimes (a) a diffusion controlled process at the initial stages and (b) at longer times, an exponential behavior where the arriving chain must penetrate the barrier formed by the already adsorbed chains. The experimental data indicated that the stars penetrate this barrier faster than the linear chains. 

From the data reported in Fig. 2.2 and from spectroscopic ellipsometry measurements, the anisotropic complex optical constants of oriented PPV have been determined [32,69]. Several different data analyses, described previously, were carried out on the 7Z and T spectra in order to extract n, both below and above the HOMO-LUMO transition (transparent free-standing film and bulk material, respectively). In order to evaluate n below 1.6 eV, where the sum of 1Z and T is equal to 1 within experimental error, a numerical inversion of the 7Z and T spectra was performed by assuming k = 0... 

Wischerhoff E, Laschewsky A (1999) Polyelectrolyte adsorption onto planar surfaces a study by streaming potential and ellipsometry measurements. Colloids Surf A Physicochem Eng Aspects 159 491... 

By combination of ellipsometry and EQCM Gottesfel [24] studied the nucleation and growth of polyaniline (PANI). The mass deposited was obtained by the frequency change while the thickness resulted from the ellipsometry measurements. Therefore the variations of mass and PANI film density were followed in real time, which would otherwise be impossible with either individual technique alone. 

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. 

The difference between the values obtained for the thickness of the layers in the two methods may be attributed to the effect the AFM tip has on the molecules or to the fact that, in the ellipsometry measurements, the index of refraction chosen,... 

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]

There are several techniques available to measure the optical absorption in a-Si H. Optical transmission and reflectivity, and ellipsometry measure the high energy, high absorption transitions. In the weak absorption regime near the band edge, the measurement is made difficult by the limitation on sample thickness to a few microns. The transmitted light intensity, T, through a sample is approximately. 

The aminosilane coating PF8TAS has been characterized on Si(lOO) and on microengines. The AFM analysis on coated Si(lOO) confirms that the process does not generate particles. Ellipsometry measurements conducted on coated Si(lOO) in controlled humidity... 

The self-arranged ordered DNA structures decorated by Ag nanoparticles are effectively formed on the Si surface modified by APTES. The investigations have shown the commonalities and some specific features in the hybrid structures on smooth mica surface and modified Si substrates. Small number of regular structures on mica surfaces proved that binding force of DNA to the surfaces is much lower in mica-DNA system as compared to the hybrid structure based on modified Si substrates. Spectroscopic ellipsometry measurements have shown the contributions to optical response due to components in hybrid samples. 

Ellipsometry measures the change in phase and amplitude of polarised light. Assessment is by means of the deviation of a beam of light reflected from the deposit surface. 

Film thickness values were estimated by ellipsometry. The ellipsometry measurements were performed on a phase modulation Multiskop from Physik In-strumente (Model M-033k001) at 632.8 nm (He-Ne laser). The cross-section of the laser beam was about 1 mm. Measurements in air were performed at different positions (at least five) of the samples in order to check the quality of the films. 

With MAI ellipsometry measurements at a same specimen at a same location on a specimen are taken, but the angle 6 is varied. This gives a new P and A value at every angle 6. This means that more parameters can be fitted in a model that contains one or more thin films on a substrate. However, in the model some parameters can be correlated and the dependence on 0 can be limited. Haitjema and Woerlee (1989) used this method and showed that tin oxide coatings can be... 

With spectroscopic ellipsometry, measurements at a same location on a specimen are taken at several, or at continuously scanned, wavelengths. This increases the number of measured parameters however, many parameters are also wavelength dependent, so in that not much is gained. However, clearly one parameter does not change the thickness of coatings on the surface. 

Studied by the combined use of EQCM and ellipsometry measurements. In nitrated polystyrene films, increased solvation of the polymer with increasing redox cycling was observed/ The effect of electrolyte concentration and temperature on polymer swelling in TCNQ films was studied at the EQCM. In TCNQ films cation motion maintains electroneutrality within the polymer during redox cycling, and mass changes observed were found to be dominated by the concomitant movement of water of hydration. ... 

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