scholarly journals An optical examination of thin films. I.—The optical constants of mercury

1934 ◽  
Vol 145 (854) ◽  
pp. 115-126 ◽  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Constants ◽  
Relative Phase ◽  
Reflection Coefficients ◽  
Angle Of Incidence ◽  
Clean Surface ◽  
Phase Retardation ◽  
Optical Examination ◽  
Approximate Equations

Drude originally suggested that the properties of films on both absorbing and non-absorbing substrates could be studied by an optical method, since the reflecting properties of a surface are modified by the presence of a film. This method has in part been used by various workers, with some success. For liquid surfaces, or for smooth surfaces of solids, such as are obtained by cleavage or after suitable polishing, it is possible to measure “the relative phase retardation,” Δ, and “the ratio of the reflection coefficients,” tan ψ, which define the reflecting properties. From the values of Δ and ψ for a clean surface, the refractive index, n , and the absorption coefficient, k , characteristic of the material can be found from the approximate equations n = sin ϕ tan ϕ cos 2ψ/(1 + cos Δ sin 2ψ), (1.1) k = sin Δ tan 2ψ, (2.1) where ϕ is the angle of incidence.

scholarly journals Optical constants of sputtered beryllium thin films determined from photoabsorption measurements in the spectral range 20.4–250 eV

2020 ◽  
Vol 27 (1) ◽  
pp. 75-82
Author(s):  
Mikhail Svechnikov ◽  
Nikolay Chkhalo ◽  
Alexey Lopatin ◽  
Roman Pleshkov ◽  
Vladimir Polkovnikov ◽  
...  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Synchrotron Radiation ◽  
Initial Data ◽  
Absorption Coefficient ◽  
Energy Range ◽  
Transmission Coefficient ◽  
Radiation Source ◽  
Optical Constants ◽  
Free Standing

In this work, the refractive index of beryllium in the photon energy range 20.4–250 eV was experimentally determined. The initial data include measurements of the transmittance of two free-standing Be films with thicknesses of 70 nm and 152 nm, as well as reflectometric measurements of similar films on a substrate. Measurements were carried out at the optics beamline of the BESSY II synchrotron radiation source. The absorption coefficient β was found directly from the transmission coefficient of the films, and the real part of the polarizability δ was calculated from the Kramers–Kronig relations. A comparison is carried out with results obtained 20 years ago at the ALS synchrotron using a similar methodology.

Polarization Modulation Fourier Transform Infrared Ellipsometry of Thin Polymer Films

1986 ◽  
Vol 40 (4) ◽  
pp. 498-503 ◽  
Author(s):  
R. T. Graf ◽  
F. Eng ◽  
J. L. Koenig ◽  
H. Ishida
Keyword(s):  
Optical Constants ◽  
Relative Phase ◽  
Polarization Modulation ◽  
Thin Polymer Films ◽  
Phase Retardation ◽  
Photoelastic Modulator ◽  
Infrared Ellipsometry ◽  
Thin Polymer ◽  
Gold Substrates ◽  
Ft Ir

Polarization modulation infrared ellipsometric spectra were collected on an FT-IR spectrometer, with the use of two linear polarizers and a photoelastic modulator. Samples consisted of thin poly(vinyl acetate) and poly(methyl methacrylate) films on gold substrates. The relative phase retardation (delta) and relative amplitude (psi) were derived from these measurements. These spectra were superior to those from static infrared ellipsometry measurements on the same samples. The thickness and optical constants of the films were calculated from the ellipsometric measurements and compared with reference optical constant spectra.

scholarly journals Structural, Optical Constants and Photoluminescence of ZnO Thin Films Grown by Sol-Gel Spin Coating

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Abdel-Sattar Gadallah ◽  
M. M. El-Nahass
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Spectral Range ◽  
Spin Coating ◽  
Optical Constants ◽  
Sol Gel ◽  
Free Carrier ◽  
Zno Thin Films ◽  
Free Carrier Absorption

We report manufacturing and characterization of low cost ZnO thin films grown on glass substrates by sol-gel spin coating method. For structural properties, X-ray diffraction measurements have been utilized for evaluating the dominant orientation of the thin films. For optical properties, reflectance and transmittance spectrophotometric measurements have been done in the spectral range from 350 nm to 2000 nm. The transmittance of the prepared thin films is 92.4% and 88.4%. Determination of the optical constants such as refractive index, absorption coefficient, and dielectric constant in this wavelength range has been evaluated. Further, normal dispersion of the refractive index has been analyzed in terms of single oscillator model of free carrier absorption to estimate the dispersion and oscillation energy. The lattice dielectric constant and the ratio of free carrier concentration to free carrier effective mass have been determined. Moreover, photoluminescence measurements of the thin films in the spectral range from 350 nm to 900 nm have been presented. Electrical measurements for resistivity evaluation of the films have been done. An analysis in terms of order-disorder of the material has been presented to provide more consistency in the results.

Optical properties of Al-doped ZnO thin films obtained by the method of high-frequency magnetron sputtering

2021 ◽  
pp. 2150189
Author(s):  
A. Kashuba ◽  
H. Ilchuk ◽  
R. Petrus ◽  
I. Semkiv ◽  
O. Bovgyra ◽  
...  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Magnetron Sputtering ◽  
High Frequency ◽  
Optical Constants ◽  
Zno Thin Films ◽  
Optical Parameters ◽  
Single Oscillator ◽  
Doped Zno

The optical constants and thickness of Al-doped ZnO (ZnO:Al(2.5 wt.%)) thin films prepared by high-frequency magnetron sputtering method are determined. ZnO:Al thin films are crystallized in the hexagonal structure from XRD studies. The optical constants and the bandgap of the films under study have been determined. Optical properties (refractive index [Formula: see text], absorption coefficient [Formula: see text], extinction coefficient [Formula: see text], dielectric functions [Formula: see text] and optical conductivity [Formula: see text]) of thin films and thickness [Formula: see text] can be determined from the transmission spectrum. The dispersion of the refractive index was explained using a single oscillator model. Single oscillator energy and dispersion energy are obtained from fitting. Optical parameters of the films were determined using the Cauchy, Sellmeier and Wemple models. The increasing value of dispersion parameter for polycrystalline thin films than for single crystals is observed. The fundamental absorption edge position (3.26 eV) in the transmittance spectrum of studied thin films corresponds to the values that are typical for ZnO:Al compound. No significant increase of the bandgap width was revealed by comparing ZnO:Al thin films with the known results of the optical studies of ZnO thin films. Possible reasons of such behavior were analyzed and the influence of bandgap increase on spectral behavior of optical functions are investigated. The material optical parameters such as normalized integrated transmission, zero and high-frequency dielectric constant, density of state effective mass ratio were also calculated.

scholarly journals Ellipsometric Characterization of Thin Films from Multicomponent Chalcogenide Glasses for Application in Modern Optical Devices

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
R. Todorov ◽  
J. Tasseva ◽  
V. Lozanova ◽  
A. Lalova ◽  
Tz. Iliev ◽  
...  
Keyword(s):  
Thin Films ◽  
Chalcogenide Glasses ◽  
Optical Constants ◽  
Thermal Evaporation ◽  
Optical Devices ◽  
Point Of View ◽  
Angle Of Incidence ◽  
Optical Elements ◽  
Ellipsometric Characterization

A review is given on the application of the reflectance ellipsometry for optical characterization of bulk materials and thin films with thickness betweenλ/20 and 2λ(atλ=632.8 nm). The knowledge of the optical constants (refractive index,n, and extinction coefficient,k) of thin films is of a great importance from the point of view of modelling and controlling the manufacture of various optical elements, such as waveguides, diffraction gratings, and microlenses. The presented results concern the optical properties of thin films from multicomponent chalcogenide glasses on the base of As2S3and GeS2determined by multiple-angle-of-incidence ellipsometry and regarded as a function of the composition and thickness. The homogeneity of the films is verified by applying single-angle calculations at different angles. Due to decomposition of the bulk glass during thermal evaporation, an optical inhomogeneity of the thin As (Ge)-S-Bi(Tl) films is observed. The profile ofnin depth of thin As-S-Tl (Bi) films was investigated by evaporation of discrete layers. It is demonstrated that homogenous layers from the previous compounds with controlled composition can be deposited by coevaporation of As2S3and metals or their compounds (Bi, Tl, In2S3).

Optical Properties of RF-Sputtered a-SiGe:H:O Alloys

1986 ◽  
Vol 77 ◽  
Author(s):  
J. M. T. Pereira ◽  
P. K. Banerjee ◽  
S. S. Mitra
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Constants ◽  
Rf Sputtering ◽  
Normal Incidence ◽  
Reflection And Transmission ◽  
Amorphous Thin Films ◽  
Optical Gap ◽  
Transmission Measurements ◽  
Substrate Temperatures

ABSTRACTAmorphous thin films of SixGe1-x:O (x = 0.70) were prepared by RF-sputtering at several substrate temperatures. The structural properties of these films were studied by IR spectroscopy and revealed features characteristic of hydrogen and/or oxygen bonded to silicon. The optical constants (n,k) were determined from reflection and transmission measurements at near-normal incidence for photon energies in the range of 1 eV and 2.6 eV. The optical gap was derived from the Taue plot and correlated with the composition of the samples. The increase of hydrogen and/or oxygen decreases the value of the refractive index and increases the optical gap.

Heat Treatment Effect on the Structural and Optical Properties of CdGa2S4 Thin Films

2003 ◽  
Vol 17 (13n14) ◽  
pp. 771-782 ◽  
Author(s):  
M. M. El-Nahass ◽  
H. S. Soliman ◽  
E. A. A. El-Shazly
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Refractive Index ◽  
High Frequency ◽  
Optical Constants ◽  
Thermal Evaporation ◽  
Structural And Optical Properties ◽  
High Frequency Dielectric Constant ◽  
Tetragonal Crystal ◽  
Tetragonal Crystal Structure

CdGa 2 S 4 was prepared in powder form by reacting CdS and Ga 2 S 3. The powder had a tetragonal crystal structure with lattice parameters, a = 0.559 ± 0.005 nm , c = 1.008 ± 0.009 nm and c/a = 1.803. CdGa 2 S 4 films deposited by thermal evaporation of the powder were noncrystalline. After annealing, the CdGa 2 S 4 thin films contain crystals with the tetragonal crystal structure. The optical constants (the refractive index n, the absorption index k and the absorption coefficient α) were determined for CdGa 2 S 4 thin films in the thickness range 170–452 nm. It was found that both n and k are independent of the film thickness and both are slightly different as deposited and annealed films. The refractive index shows anomalous dispersion in the spectral range 300–700 nm. The high frequency dielectric constant ε∞ was determined for the as-deposited and after being annealed films. It was found that ε∞ = 5.12 and 5.52 for the as-deposited and after being annealed films respectively. Graphical representations of (αhν)r = f(hν) yield three linear parts, indicating the existence of two indirect and one direct allowed transitions. The values of [Formula: see text], [Formula: see text] and [Formula: see text] for CdGa 2 S 4 for the as-deposited and annealed films are presented.

Substrate Temperature Effect on Optical Constants of Gd2O3 Thin Films

2010 ◽  
Vol 442 ◽  
pp. 96-101 ◽  
Author(s):  
M.F. Wasiq ◽  
M.Y. Nadeem ◽  
Franck Chollet ◽  
S. Atiq
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Substrate Temperature ◽  
Band Gap ◽  
Extinction Coefficient ◽  
Optical Constants ◽  
Urbach Energy ◽  
Band Gap Energy ◽  
Oxide Material ◽  
Atomic Force

Effect of substrate temperature on lanthanide oxide material Gd2O3 thin films deposited by e-beam evaporation has been reported in the present work. Optical properties and surface morphology of as deposited films have been measured using spectrophotometry and atomic force microscopy respectively. Optical constants such as refractive index, extinction coefficient, band gap and Urbach energy have been determined by analysis of experimentally recorded absorption, transmittance and reflection data in wavelength range 200-800nm. Optical band gap energy shows decreasing while Urbach energy shows increasing behavior with increasing temperature. Extinction coefficient and refractive index with varying wavelengths are also calculated. Surface topographies of all samples are studied by atomic force microscope (AFM) and root mean square (RMS) value of roughness is observed increasing with increasing substrate temperature.

scholarly journals The Effect of Chlorine Concentration on the Optical Constants of SnS Thin Films

2011 ◽  
Vol 8 (2) ◽  
pp. 566-570
Author(s):  
Baghdad Science Journal
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Constants ◽  
Skin Depth ◽  
Chlorine Concentration ◽  
Chemical Spray Pyrolysis ◽  
Chemical Spray ◽  
Sns Thin Films ◽  
Effect Of Chlorine

Chlorine doped SnS have been prepared utilizing chemical spray pyrolysis. The effects of chlorine concentration on the optical constants were studied. It was seen that the transmittance decreased with doping, while reflectance, refractive index, extinction coefficient, real and imaginary parts of dielectric constant were increased as the doping percentage increased. The results show also that the skin depth decrease as the chlorine percentage increased which could be assure that it is transmittance related.

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