scholarly journals Optics of Inhomogeneous Thin Films with Defects: Application to Optical Characterization

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 22
Author(s):  
Ivan Ohlídal ◽  
Jiří Vohánka ◽  
Martin Čermák
Keyword(s):  
Thin Films ◽  
Thickness Distribution ◽  
Uniaxial Anisotropy ◽  
Optical Characterization ◽  
Diffraction Theory ◽  
Matrix Formalism ◽  
Transition Layers ◽  
Theoretical Approaches ◽  
Boundary Roughness

This review paper is devoted to optics of inhomogeneous thin films exhibiting defects consisting in transition layers, overlayers, thickness nonuniformity, boundary roughness and uniaxial anisotropy. The theoretical approaches enabling the inclusion of these defects into formulae expressing the optical quantities of these inhomogeneous thin films are summarized. These approaches are based on the recursive and matrix formalisms for the transition layers and overlayers, averaging of the elements of the Mueller matrix using local thickness distribution or polynomial formulation for the thickness nonuniformity, scalar diffraction theory and Rayleigh-Rice theory or their combination for boundary roughness and Yeh matrix formalism for uniaxial anisotropy. The theoretical results are illustrated using selected examples of the optical characterization of the inhomogeneous polymer-like thin films exhibiting the combination of the transition layers and thickness nonuniformity and inhomogeneous thin films of nonstoichiometric silicon nitride with the combination of boundary roughness and uniaxial anisotropy. This characterization is realized by variable angle spectroscopic ellipsometry and spectroscopic reflectometry. It is shown that using these optical techniques, the complete optical characterization of the mentioned thin films can be performed. Thus, it is presented that the values of all the parameters characterizing these films can be determined.

scholarly journals Optical Characterization of Non-Stoichiometric Silicon Nitride Films Exhibiting Combined Defects

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 416 ◽  
Author(s):  
Jiří Vohánka ◽  
Ivan Ohlídal ◽  
Miloslav Ohlídal ◽  
Štěpán Šustek ◽  
Martin Čermák ◽  
...  
Keyword(s):  
Experimental Data ◽  
Silicon Nitride ◽  
Least Squares Method ◽  
Uniaxial Anisotropy ◽  
Optical Characterization ◽  
Inhomogeneous Layer ◽  
Matrix Formalism ◽  
Random Roughness ◽  
Silicon Nitride Films

The study was devoted to optical characterization of non-stoichiometric silicon nitride films prepared by reactive magnetron sputtering in argon-nitrogen atmosphere onto cold (unheated) substrates. It was found that these films exhibit the combination of three defects: optical inhomogeneity (refractive index profile across the films), uniaxial anisotropy with the optical axis perpendicular to the boundaries and random roughness of the upper boundaries. The influence of the uniaxial anisotropy was included into the corresponding formulae of the optical quantities using the matrix formalism and the approximation of the inhomogeneous layer by a multilayer system consisting of large number thin homogeneous layers. The random roughness was described using the scalar diffraction theory. The processing of the experimental data was performed using the multi-sample modification of the least-squares method, in which experimental data of several samples differing in thickness were processed simultaneously. The dielectric response of the silicon nitride films was modeled using the modification of the universal dispersion model, which takes into account absorption processes corresponding to valence-to-conduction band electron transitions, excitonic effects and Urbach tail. The spectroscopic reflectometric and ellipsometric measurements were supplemented by measuring the uniformity of the samples using imaging spectroscopic reflectometry.

Structural and Optical Characterization of Zinc Telluride Thin Films

2013 ◽  
Vol 665 ◽  
pp. 254-262 ◽  
Author(s):  
J.R. Rathod ◽  
Haresh S. Patel ◽  
K.D. Patel ◽  
V.M. Pathak
Keyword(s):  
Thin Films ◽  
Extinction Coefficient ◽  
Nir Spectroscopy ◽  
Optical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Evaporation Technique ◽  
Film Form ◽  
Znte Thin Films

Group II-VI compounds have been investigated largely in last two decades due to their interesting optoelectronic properties. ZnTe, a member of this family, possesses a bandgap around 2.26eV. This material is now a day investigated in thin film form due to its potential towards various viable applications. In this paper, the authors report their investigations on the preparation of ZnTe thin films using vacuum evaporation technique and their structural and optical characterizations. The structural characterization, carried out using an X-ray diffraction (XRD) technique shows that ZnTe used in present case possesses a cubic structure. Using the same data, the micro strain and dislocation density were evaluated and found to be around 1.465×10-3lines-m2and 1.639×1015lines/m2respecctively. The optical characterization carried out in UV-VIS-NIR region reveals the fact that band gap of ZnTe is around 2.2eV in present case. In addition to this, it was observed that the value of bandgap decreases as the thickness of films increases. The direct transitions of the carries are involved in ZnTe. Using the data of UV-VIS-NIR spectroscopy, the transmission coefficient and extinction coefficient were also calculated for ZnTe thin films. Besides, the variation of extinction coefficient with wavelength has also been discussed here.

Simulation and prediction of optical characterization of casting (Adamantan-Fulgide) thin films using (CTANNs) approach

2019 ◽  
Vol 33 (11) ◽  
pp. 1950093 ◽  
Author(s):  
A. M. A. EL-Barry ◽  
D. M. Habashy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Back Propagation ◽  
Optical Characterization ◽  
Experimental Information ◽  
Training Algorithm ◽  
Energy Gaps ◽  
Resilient Back Propagation ◽  
Good Agreement

For reinforcement, the photochromic field and the cooperation between the theoretical and experimental branches of physics, the computational, theoretical artificial neural networks (CTANNs) and the resilient back propagation (R[Formula: see text]) training algorithm were used to model optical characterizations of casting (Admantan-Fulgide) thin films with different concentrations. The simulated values of ANN are in good agreement with the experimental data. The model was also used to predict values, which were not included in the training. The high precision of the model has been constructed. Moreover, the concentration dependence of both the energy gaps and Urbach’s tail were, also tested. The capability of the technique to simulate the experimental information with best accuracy and the foretelling of some concentrations which is not involved in the experimental data recommends it to dominate the modeling technique in casting (Admantan-Fulgide) thin films.

Optical characterization of thin films by guided waves

1989 ◽  
Vol 28 (14) ◽  
pp. 2918 ◽  
Author(s):  
Emile Pelletier ◽  
F. Flory ◽  
Y. Hu
Keyword(s):  
Thin Films ◽  
Guided Waves ◽  
Optical Characterization

Optical characterization of CuIn1−xGaxSe2 alloy thin films by spectroscopic ellipsometry

2003 ◽  
Vol 94 (2) ◽  
pp. 879-888 ◽  
Author(s):  
P. D. Paulson ◽  
R. W. Birkmire ◽  
W. N. Shafarman
Keyword(s):  
Thin Films ◽  
Spectroscopic Ellipsometry ◽  
Optical Characterization

Preparation and Optical Characterization of PMMA Thin Films of C1

2021 ◽  
Vol 400 (1) ◽  
pp. 2100150
Author(s):  
Kalpana Sharma ◽  
Raveendra Melavanki ◽  
Basappa C Yallur ◽  
Raviraj Kusanur ◽  
N R Patil
Keyword(s):  
Thin Films ◽  
Optical Characterization
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