Constants Of Thin Metallic Films Research Articles

Measurement of the Optical Constants of Thin Metal Films by THz Differential Time Domain Spectroscopy

Three kinds of nanometer-scale metal films (Cr, Ni and Ti) with different thicknesses are fabricated. The complex refractive indices of the three metal films are quantitatively measured by using THz differential time-domain spectroscopy (THz-DTDS). The orders of the complex refractive indices of the thin metal films are equal to those of the reported values. Our results validated that THz-DTDS can be used to study the features of the ultra-thin metal films.

General approach to reliable characterization of thin metal films

Optical constants of thin metal films are strongly dependent on deposition conditions, growth mode, and thickness. We propose a universal characterization approach that allows reliable determination of thin metal film optical constants as functions of wavelength and thickness. We apply this approach to determination of refractive index dispersion of silver island films embedded between silica layers.

Determination of thickness and optical constants of thin metal films with an extended ATR spectrum

An extended attenuated total reflection (ATR) spectrum, which consists of a surface plasmon resonance (SPR) dip and a total internal reflection (TIR) step, is used to determine the optical constant and the thickness of a thin metal film at a given frequency in the conventional Kretschmann configuration. Previous research has shown that two sets of solutions for the optical constant and thickness can be obtained from a SPR dip, and ambiguity should be removed by carrying out another angular scan process or employing a more complicated structure. However, we find that the true solution can be simply selected by a new parameter that denotes the TIR step change. Our method can avoid not only the troubles caused by the double-scan techniques but also the increased difficulties due to the existence of an additional polymer film in a single-scan method.

Determining the optical constants of thin metallic films while they are being deposited in vacuum

This paper proposes a method of monitoring the optical constants and thickness of a layer while it is being deposited in vacuum, using measurements of the reflectance and transmittance on two substrates with different refractive indices. All four measured signals, as well as the background-illumination signal, are monitored by a monochromatic spatial radiation detector. The system was certified using nickel films up to 80nm thick.

Optical constants of evaporated gold films measured by surface plasmon resonance at telecommunication wavelengths

We report the first measurement of the optical constants of evaporated gold films by using the surface plasmon resonance curve fitting method with an attenuated total reflection device from 16 to 70 nm thickness at telecommunication wavelengths. The results that were obtained by surface plasmon resonance measurement are in good agreement with those obtained by ellipsometry. Until now, optical constants of thin metal films are known to change according to the thickness due to the variation of the electrical resistivity. This phenomenon is also verified in this study by a simple surface plasmon resonance measurement. It is observed that for the gold films of thicknesses of less than 20 nm, the real part of the refractive index increases and the imaginary part decreases with decreasing film thickness.

Improved SPR technique for determination of the thickness and optical constants of thin metal films

A novel method with single-wavelength light is developed to determine the optical constants and the thickness of a thin metal film. It bases on a new geometry that consists of a coupling prism, a transparent coating layer directly deposited onto the prism base, a thin metal film to be detected, and the air. The attenuated total reflection technique is employed in our configuration to excite two different kinds of surface plasmon waves simultaneously. As a result, the reflection curve shows two obvious surface plasmon resonant dips. Using the Chen's et al. (Opt. Soc. Am. 71 189, 1981) method, we can obtain two sets of e(ω) and thickness of the thin metal film through one resonant dip (surface plasmon), then the real value can be determined through the other resonant dip (modified long-range surface plasmon). Compared to conventional double wavelength method and the double-medium technique (Yang et al. Appl. Opt. 27 11, 1988), the present single-scan method avoids both the ambiguity of different conditions caused by two-scan technique, and the dispersion problem with different light wavelength.

Fiber-optic surface-plasmon resonance for the determination of thickness and optical constants of thin metal films

We demonstrate that the thickness and the dielectric constants of thin gold films deposited on the surface of a fiber core can be quantitatively determined as a single set of solutions by the simple measurement of the fiber-optic surface-plasmon resonance responses. This method is capable of directly characterizing metal films with curved surfaces: this is very hard to perform by use of the conventional optical techniques of reflectometry and ellipsometry. The theoretical errors for the experimental fiber are estimated to be within d +/- 2%, epsilon(r) +/- 1%, and epsilon(i) +/- 15%.

Simple method for determining the optical constants of thin metallic films from transmittance measurements

A method for the determination of the optical constants of thin metal films on transparent substrates is proposed. It requires measurements at normal incidence of the transmittance from the specimen itself and when coated with a thin transparent layer. A procedure is given for determining the correct solutions for the indices of refraction and absorption and also for accurately fixing the thickness of the film. Advantage of the present method over existing methods is readily available measurement facilities. The method has been applied successfully to films of gold.

Evanescent wave spectroscopy for the determination of the optical constants of thin silver films deposited on a silver-halide fiber

An unclad silver-halide fiber was coated with a 0.1-microm silver layer and immersed in ethyl alcohol, and the fiber transmission in the range 2-20 microm was measured. The loss, induced by the metallic layer, was used to calculate the extinction coefficient, kappa', and the index of refraction, n', of the layer by fitting the experimental data with the time-independent perturbation theory in the complex region. The dependence of the extinction coefficient on the wavelength was found to be logarithmic, kappa'(lambda) = kappa(0)' exp(a lambda), and not linear, as predicted by others. This simple technique may be used to study the optical constants of thin metallic films.

Optical methods for thickness measurements on thin metal films

The thickness and the dielectric constants of thin metal films on glass substrates are determined by two different methods. The first method is a combination of transmission and ellipsometer measurements (TELL method) and the second is based on attenuated total reflection (ATR method in the Kretschmann arrangement). For comparison, both methods are applied to gold films within a thickness range of 20-80 nm. Furthermore, the TELL method was applied to chromium films of thicknesses up to 150 nm. All experiments are done with a He-Ne laser at 633-nm wavelength.

Use of exchanging media in ATR configurations for determination of thickness and optical constants of thin metallic films

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Fuzi Yang, Zhuangqi Cao, and Junxin Fang, "Use of exchanging media in ATR configurations for determination of thickness and optical constants of thin metallic films," Appl. Opt. 27, 11-12 (1988) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Use of surface plasma waves for determination of the thickness and optical constants of thin metallic films

The surface plasma wave technique for determining the dielectric constant ∊(ω) and the thickness d of a metal film without a preset expression for ∊(ω) is discussed. Two sets of solutions can be derived at a given frequency. By comparing d determined at another frequency, the correct ∊(ω) and d solution can be determined.

Use of surface plasma waves for determination of the thickness and optical constants of thin metallic films. (UDA)

1991 saw the 300th anniversary of the death of Robert Boyle, the man who founded the Royal Society and discovered the inverse relationship between the volume and the pressure of a gas. Boyle's Law, P1V1 = P2V2, is as familiar to modern GCSE students as it is to engineers, and has helped scientists comprehend and predict the behaviour of gasses ever since it was discovered. In this article Noel West, managing director of vacuum pump manufacturer Werner Rietschle, takes a look at how Boyle's initial discoveries set the scene for the development of the modern vacuum pump.

Ein verfahren zur bestimmung der optischen konstanten dünner metallfilme aus transmissionsmessungen und seine anwendung auf Cs-filme

A semi-graphical method is described with which the optical constants of thin metallic films can be obtained from transmission measurements with parallel and perpendicular polarized light. The equations used in the calculations are those of the classical optics of thin metallic films and were used without further approximations. The method is applied to Cs films of thicknesses 14–160 nm and for photon energies between 1.5 and 3.8 eV.

Numerical evaluation of the optical constants of thin metallic films

A refined numerical technique for the evaluation of the complex refractive index of metals from measurements of the absolute reflectances and transmittance of a thin film is described. The technique makes use both of the Fortran language facility in the manipulation of complex numbers and of a modern rapid-convergence minimization procedure. The results of the application of the technique to the evaluation both of data from the literature and measurements obtained from an absolute photometer are also discussed.

Comparative study of Vašíček's theory, Murmann-Försterling's theory and single reflection theory of thin film optics

Vašíček's theory and the Murmann-Försterling theory for determining the optical constants of thin metallic films, using ellipsometric parameters, are compared with the single reflection theory. Optical constants for thin metallic films are theoretically evaluated for wide ranges of azimuth ψ, phase difference Δ and film thickness/wavelength factor; the three theories are studied by comparing optical constants obtained for various values of the film thickness/wavelength factor. It is shown that the three theories lead to almost the same values of optical constants for certain ranges of variables. It is further shown that in other ranges, Vašíček's theory and the Murmann-Försterling theory agree with each other or one of them agrees with the single reflection theory. However, the study is restricted to the following values only: angle of incidence 75°, and refractive indices of substrate and air 1.500 and 1.000, respectively.

The effective optical constants of thin metal films in island form

The Maxwell Garnett theory has been extended by considering different possible values for the refractive index of the film interspaces. The effects of this on the values of ne and ke for island films are investigated and comparison is made with the experimental data of Philip and Trompette.

804. On the variation with wavelength of the opitcal constants of thin metallic films: G. Rasigni and P. Rouards, J. Opt. Soc. Amer., 53 (5), May 1963, 604

804. On the variation with wavelength of the opitcal constants of thin metallic films: G. Rasigni and P. Rouards, J. Opt. Soc. Amer., 53 (5), May 1963, 604

On the Variation with Wavelength of the Optical Constants of Thin Metallic Films

Assuming that a thin metallic layer may be characterized, from the optical point of view, by its thickness d, its refractive index ν, and its index of extinction κ, the curves representing 2νκd and (ν2 − κ2 − ∊a)d, where ∊a is a constant, are plotted against the wavelength for very thin layers of gold, silver, copper, iron, nickel, and cobalt, thermically evaporated and investigated in a vacuum of some 2 to 3 × 10−6 Torr. The analogy which the curves relating to the thin layers of the three first named of these metals exhibit with the characteristic curves of a resonator having a well-defined natural frequency and large damping is pointed out. The experimentally determined variations of the optical constants of these thin films with the wavelength of light can be interpreted by use of the discontinuous-structure microcrystallite-assembly description in the theory of David. Agreement is satisfactory with the supposition that the microcrystallites have the form of ellipsoids of revolution or even of spheres. In the case of gold and copper, the phenomena are perturbed by a maximum of the characteristic absorption caused by an electronic transition that is located in the visible portion of the spectrum.

On the Measurement of Electric Constants of Thin Metallic Films

The present work deals with Hall effect and specific conductivity measurements in the case of a nonuniform current density field (that is, when the specimen is not a parallelepiped but has irregularly waved surfaces). It is then impossible to measure separately RH (Hall coefficient) and σ (conductivity); it is possible, however, to get their product, the Hall mobility of the carriers. These conclusions are important when dealing with thin films, where the actual geometry of the surface is completely unknown. The preceding remarks are used to interpret the results of some experiments on Au films evaporated on mica. An almost constant mobility is found versus mean thickness, but its magnitude is about ¼ the bulk mobility. This behavior raises some question about the structure of thin films, and some connection seems to hold between the experiments here described and the results of the measurements of the optical constants of metals.