Evaluation of spectral dispersion of optical constants of a-Se films from their normal-incidence transmittance spectra using Swanepoel algebraic envelope approach

Pb(Zr1-x, Tix)O3 (x = 0.05) with pyroelectric properties have been synthesized by sol–gel technique at low temperatures. XRD results indicate that the powder has perovskite structure without secondary phases and the average of particle size was estimated to be about 40 nm in diameters. The optical constants such as refractive index, n, extinction coefficient, k, and the dielectric function of PZT nanopowders have been investigated by Fourier transmittance infrared (FTIR) spectrum and Kramers–Kronig (KK) analysis program. The use of the KK method to analyze the normal incidence infrared (IR) reflectance spectra with a single resonance has also been described. The results indicated that the optical constant increases slowly as temperature of calcinations increases.

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Spectroscopic Ellipsometry and Raman Studies on Sputtered TiO2 Thin Films

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.106.127 ◽

2005 ◽

Vol 106 ◽

pp. 127-132

Author(s):

B. Karunagaran ◽

Young Kuk Kim ◽

Kyung Hae Kim ◽

S.K. Dhungel ◽

J.S. Yoo ◽

...

Keyword(s):

Raman Scattering ◽

Spectroscopic Ellipsometry ◽

Optical Constants ◽

Tio2 Thin Film ◽

Normal Incidence ◽

Silicon Substrates ◽

Titanium Dioxide Films ◽

Sputtering Pressure ◽

Deposited Films ◽

Post Deposition

Titanium dioxide films were deposited using DC magnetron sputtering technique onto silicon substrates at ambient temperature and at an oxygen partial pressure of 7×10 –5 mbar and sputtering pressure (Ar + O2) of 1×10–3 mbar. The composition of the films, analyzed by Auger Electron Spectroscopy (AES), revealed the stoichiometry with an O and Ti ratio of 2.08. The optical constants of the as-deposited TiO2 thin film were determined by Spectroscopic Ellipsometry in the photon energy range 1.2 to 5.5 eV at room temperature. The measured dielectric-function spectra reveal distinct structures at energies of the E1, E1+D1 and E2 critical points due to interband transitions. The Dielectric constant values were found to be substantially lower than those for the bulk TiO2. The dielectric related optical constants, such as the refractive index, extinction coefficient, absorption coefficient and normal incidence of reflectivity are presented and analyzed. The deposited films were calcinated at 673 and 773 K. The influence of post-deposition calcination on the Raman scattering of the films was studied. The existence of Raman active modes A1g, B1g and Eg corresponding to the Raman shifts are reported in this paper. The improvement of crystallinity of the TiO2 films as shown by the Raman scattering studies has also been reported.

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A SIMPLE MODEL FOR OBTAINING OPTICAL CONSTANTS OF POROUS SILICON

Modern Physics Letters B ◽

10.1142/s0217984901002440 ◽

2001 ◽

Vol 15 (17n19) ◽

pp. 745-748

Author(s):

JAIME TORRES ◽

JAIRO GIRALDO

Keyword(s):

Thin Film ◽

Thin Films ◽

Simple Model ◽

Porous Silicon ◽

Optical Constants ◽

Normal Incidence ◽

Sample Thickness ◽

Infinite Dimensions ◽

Simple Method ◽

Harmonic Oscillator Model

A simple method is proposed to calculate optical constants from porous silicon (PS) thin films, out of the simulation of normal incidence reflection spectrums. In the optical system used in this model, PS one considers as a homogeneous uniform thin film when deposited upon a substrate with semi-infinite dimensions. The PS and Substrate refractive indexes are obtained using the Simple Harmonic Oscillator Model, proposed by Wemple and DiDomenico. In addition, the absorption coefficient and sample thickness are also be obtained. The model to calculate the optical constants of some samples prepared at different anodisation times is used.

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Optical Properties of Thin Germanium Films

Australian Journal of Physics ◽

10.1071/ph720743 ◽

1972 ◽

Vol 25 (6) ◽

pp. 743 ◽

Cited By ~ 6

Author(s):

RE Denton ◽

SG Tomlin

Keyword(s):

Optical Constants ◽

Wavelength Region ◽

Normal Incidence ◽

Random Structure ◽

Amorphous Films ◽

Amorphous Germanium ◽

Long Wavelength ◽

Wide Range ◽

Germanium Films ◽

Absorption Law

The refractive and absorption indices of thin amorphous germanium films have been obtained from measurements, at normal incidence, of reflectances and transmittances over a wide range of wavelengths. The optical constants derived were in general agreement with the results of Tauc et al. (1964) except in the long wavelength region beyond the absorption edge. The absorption followed the law for indirect transitions from 0�72 to 1�1 eV, and the same law, but with a change in the slope of the curves, from 1�1 eV to the limit of our measurements at about 1�5 eV. The results are consistent with the view that the energy band structure of amorphous germanium is not essentially different from that of the crystalline material, except that the random structure eliminates the restriction that allows only direct transitions with the result that the absorption law for amorphous films is of the same form as for indirect transitions in crystals.

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