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Investigation into the effect of substrate material on microstructure and optical properties of thin films deposited via magnetron sputtering technique
, Article Ceramics International ; 2021 ; 02728842 (ISSN) ; Nemati, A ; Hadi, I ; Mirdamadi, Sh ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study aims at investigating the effect of the substrate material on growth mechanism and also microstructure of Ta2O5 thin films. For this purpose, atomic force microscopy, scanning electron microscopy, and interferometry analyses were implemented to reveal the influence of silicon wafer and amorphous BK7 glass substrates on the nucleation and growth mechanisms of Ta2O5 thin films deposited via the radio frequency magnetron sputtering technique. Results indicated that those films with finer morphologies had relatively higher nucleation densities. Compared with BK7 glass substrate, crystals formed on the silicon wafer were shown to be finer and had lower mean areas in more nucleation...
Elastic responses of bi-material media reinforced by interfacial thin films under asymmetric loading
, Article International Journal of Solids and Structures ; Volume 254-255 , 2022 ; 00207683 (ISSN) ; Jarfi, H ; Eskandari, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, the elastic solution to the problem of an isotropic bi-material full-space reinforced by a perfectly bonded thin film across the media interface and subjected to arbitrary asymmetric interfacial loading is addressed. To not include any simplifications, the thin film is first considered as a layer having a finite thickness, and with the aid of Fourier expansion of Muki's potential functions in Hankel transformed space, the formulation of the problem is obtained for a tri-material full-space. Then, knowing that the flexural stiffness of the thin film is negligible, its thickness and shear modulus are assumed to tend to zero and infinity, respectively, such that its in-plane...
Design of high-sensitivity surface plasmon resonance sensor based on nanostructured thin films for effective detection of DNA hybridization
, Article Plasmonics ; Volume 17, Issue 4 , 2022 , Pages 1831-1841 ; 15571955 (ISSN) ; Zangenehzadeh, S ; Keshavarz, A ; Sharif University of Technology
Springer
2022
Abstract
As developed countries’ ability to control infectious diseases increases, it has become clear that genetic diseases are a major cause of disability, death, and human tragedy. Coronavirus has recently spread throughout the world, and the capacity to detect low concentrations and virus changes can help to prevent the sickness from spreading further. In this paper, a surface plasmon resonance sensor based on nanostructured thin films and graphene as a 2D material has been designed with high sensitivity and accuracy to identify DNA-based infectious diseases such as SARS-CoV-2. The transfer matrix method assesses the effects of different structural factors, including nanolayer thickness on the...
Investigation into the effect of substrate material on microstructure and optical properties of thin films deposited via magnetron sputtering technique
, Article Ceramics International ; Volume 48, Issue 5 , 2022 , Pages 6277-6286 ; 02728842 (ISSN) ; Nemati, A ; Hadi, I ; Mirdamadi, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study aims at investigating the effect of the substrate material on growth mechanism and also microstructure of Ta2O5 thin films. For this purpose, atomic force microscopy, scanning electron microscopy, and interferometry analyses were implemented to reveal the influence of silicon wafer and amorphous BK7 glass substrates on the nucleation and growth mechanisms of Ta2O5 thin films deposited via the radio frequency magnetron sputtering technique. Results indicated that those films with finer morphologies had relatively higher nucleation densities. Compared with BK7 glass substrate, crystals formed on the silicon wafer were shown to be finer and had lower mean areas in more nucleation...
Deposition of Absorber layer of Copper Indium Gallium Di-Selenide with Solution based Method for Solar Cell Applications
, M.Sc. Thesis Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Dehghani, Mehdi (Supervisor)
Abstract
In recent years, the use of thin film solar cells has been widely considered due to the ability of their solution-based coatings. One of these is the chalcopytie solar cell copper indium gallium di-selenide (CIGS). The absorber layer of copper indium gallium diselenide was carried out by a spray pyrolysis method. then by using a chemical bath deposition, a buffer layer was fabricated to form the p-n junction. Subsequently, silver nanoparticles and zinc oxide alumina sputtering were used to form a transparent conductive film. with using the substrate Molybdenum and by optimizing the test conditions, such as temprature and deposition time to adjust thickness of layers, Cell with an...
Synthesis and properties of Fe-Pd Shape Memory thin Films by Electrodeposition
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
In this study, an alkaline bath for co-deposition of Fe and Pd was selected. In order to investigate the mechanism of deposition, each of the metals iron and palladium electrodeposited from selected bath separately; and the kinetics of electrodeposition by electrochemical techniques such as linear voltammetry, cyclic voltammetry, chronoamperometry and chronopotentiometry were evaluated. Electrodeposition processes of Fe, Pd and their alloy were irreversible and under diffusion of reducing agents are controlled. Moreover the electroreduction of palladium from utilized bath was performed in two steps. At following, the mechanism of iron– palladium alloy electrocrystallization was discussed and...
Boussinesq indentation of a transversely isotropic half-space reinforced by a buried inextensible membrane
, Article Applied Mathematical Modelling ; Vol. 38, issue. 7-8 , April , 2014 , p. 2163-2172 ; Ahmadi, S. F ; Eskandari, M ; Sharif University of Technology
Abstract
The normal indentation of a rigid circular disk into the surface of a transversely isotropic half-space reinforced by a buried inextensible thin film is addressed. By virtue of a displacement potential function and the Hankel transform, the governing equations of this axisymmetric mixed boundary value problem are represented as a dual integral equation, which is subsequently reduced to a Fredholm integral equation of the second kind. Two important results of the contact stress distribution beneath the disk region as well as the equivalent stiffness of the system are expressed in terms of the solution of the Fredholm integral equation. When the membrane is located on the surface or at the...
Optimization of sputtering parameters for the deposition of low resistivity indium tin oxide thin films
, Article Acta Metallurgica Sinica (English Letters) ; Vol. 27, issue. 2 , Apr , 2014 , p. 324-330 ; Bagheri, B ; Yazdanfar, P ; Rashidian, B ; Sasanpour, P ; Sharif University of Technology
Abstract
Indium tin oxide (ITO) thin films have been deposited using RF sputtering technique at different pressures, RF powers, and substrate temperatures. Variations in surface morphology, optical properties, and film resistances were measured and analyzed. It is shown that a very low value of sheet resistance (1.96 ω/sq.) can be achieved with suitable arrangement of the deposition experiments. First, at constant RF power, deposition at different pressure values is done, and the condition for achieving minimum sheet resistance (26.43 ω/sq.) is found. In the next step, different values of RF powers are tried, while keeping the pressure fixed on the previously found minimum point (1-2 Pa). Finally,...
Effect of geometry, joule heating, and critical current on the responsivity of MOD superconducting transition edge sensors
, Article Journal of Superconductivity and Novel Magnetism ; Volume 26, Issue 4 , April , 2013 , Pages 831-834 ; 15571939 (ISSN) ; Moftakharzadeh, A ; Kokabi, A ; Vesaghi, M. A ; Fardmanesh, M ; Sharif University of Technology
2013
Abstract
By fabrication of several bolometric detectors on the YBCO film made of Metal-Organic Deposition (MOD) and the effect of pattering and film parameters on the optical responsivity of transition edge sensors is investigated. The low cost nonfluorine (MOD) method has been applied to fabricate YBCO thin films with different patterning parameters. The measurement results of the optical responsivity versus modulation frequency up to 100 KHz for these devices are reported
Accurate numerical model for surface scattering, grain boundary scattering, and anomalous skin effect of copper wires
, Article Proceedings - Winter Simulation Conference ; January , 2013 , Pages 209-210 ; 08917736 (ISSN) ; 9781467348416 (ISBN) ; Sarvari, R ; Akbarzadeh, A ; Rostami, M ; Sharif University of Technology
2013
Abstract
In this paper we have studied both DC size effect and anomalous skin effect caused by surface and grain boundary scattering on the resistivity of Cu thin films by a Monte Carlo method. Contribution of each scattering mechanism and the interaction between them are analyzed separately. A simple and fast numerical recursive method is also introduced to guess the structure of electric field and distribution of current inside the thin film to evaluate the surface resistance instead of complicated analytical formulas
Late-stage evolution of thin liquid coating films over step topographies
, Article Advanced Materials Research ; Volume 569 , 2012 , Pages 560-563 ; 10226680 (ISSN) ; 9783037854808 (ISBN) ; Moosavi, A ; Sharif University of Technology
2012
Abstract
Mesoscopic hydrodynamic equations are solved to investigate late-stage evolution of thin liquid films over step topographies. Different geometrical parameters including step height and initial position and configuration of resultant masses of dewetting (droplets) are probed to find their effects on the mass evolution of the system. Our results indicate that increasing the step height and locating the droplets close to the step enhance the dynamics and accelerate smaller droplet collapse
A comparison of carbon coated and uncoated 316L stainless steel for using as bipolar plates in PEMFCs
, Article Journal of Alloys and Compounds ; Volume 509, Issue 27 , July , 2011 , Pages 7400-7404 ; 09258388 (ISSN) ; Yari, M ; Afshar, A ; Jafarian, M ; Eshghabadi, M ; Sharif University of Technology
2011
Abstract
Two kinds of carbon coated and uncoated 316L stainless steel are studied to use as bipolar plates in fuel cells. The results show that the conductive amorphous carbon film has a low corrosion rate in simulated PEMFC environment. Rather long term potentiostatic tests and SEM investigations indicate that carbon thin films can be a good candidate to use as bipolar plate
Axisymmetric response of a bi-material full-space reinforced by an interfacial thin film
, Article International Journal of Solids and Structures ; Volume 90 , July , 2016 , Pages 251–260 ; 00207683 (ISSN) ; Samea, P ; Eskandari, M ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Analytical treatment of a linear elastic isotropic bi-material full-space reinforced by an interfacial thin film under axisymmetric normal loading is addressed. The thin film is modeled as an extensible membrane perfectly bonded to the half-spaces. By virtue of Love's potential function and Hankel integral transform, elastic fields of the system are explicitly written in the form of semi-infinite line integrals. The analytical results are verified by the special cases corresponding to the surface stiffened half-space and classical bi-material problem. The limiting cases of reinforced homogeneous full-space and inextensible membrane are presented and discussed. The proposed formulation is...
Numerical study of material properties, residual stress and crack development in sintered silver nano-layers on silicon substrate
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1037-1047 ; 10263098 (ISSN) ; Movahhedy, M. R ; Akbari, J ; Alemohammad, H ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
In order to improve the performance of thin film devices, it is necessary to characterize their mechanical, as well as electrical, properties. In this work, a model is developed for analysis of the mechanical and electrical properties and the prediction of residual stresses in thin films of silver nanoparticles deposited on silicon substrates. The model is based on inter-particle diffusion modeling and finite element analysis. Through simulation of the sintering process, it is shown how the geometry, density, and electrical resistance of the thin film layers are changed by sintering conditions. The model is also used to approximate the values of Young's modulus and the generated residual...
Improving the photocatalytic activity of graphene oxide/ZnO nanorod films by UV irradiation
, Article Applied Surface Science ; Volume 371 , 2016 , Pages 592-595 ; 01694332 (ISSN) ; Akhavan, O ; Sharif University of Technology
Elsevier
2016
Abstract
Graphene oxide (GO) sheets with a low concentration (∼1 wt%) were deposited on surface of hydrothermally synthesized ZnO nanorod films. The deposited films were heat treated at 450 °C in order to achieve suitable GO/ZnO hybrid thin films for photocatalytic purposes. The photocatalytic activity of the nanocomposite films was investigated based on degradation of methylene blue (MB) dye which is a typical pollutant model. The GO/ZnO hybrid thin films could degrade higher MB (∼90%) than the bare ZnO nanorods (which showed only ∼75% degradation) after 450 min UV irradiation. A further significant improvement (resulting in a nearly complete degradation of MB) was achieved by exposing the GO/ZnO...
Stress gradient interpretation of boundary layers in passivated thin films
, Article International Journal of Non-Linear Mechanics ; Volume 81 , 2016 , Pages 139-146 ; 00207462 (ISSN) ; Soleymani Shishvan, S ; Assempour, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
A continuum implementation of stress gradient plasticity is established to analyze passivated thin films under tension. It is verified and evaluated by investigation of the tensile response of passivated Cu films with different thicknesses and grain sizes. The material parameters are fitted to the stress-strain experimental data, while the length scale parameter is directly characterized from the corresponding available discrete dislocation predictions. The numerical solutions give rise to boundary layers near the interface between film and passivation. This prediction is consistent with the formation of dislocation pileups at the film-passivation interface and also is responsible for the...
Microstructure and thermochromic properties of VOX–WOX–VOX ceramic thin films
, Article Applied Physics A: Materials Science and Processing ; Volume 122, Issue 3 , 2016 , Pages 1-5 ; 09478396 (ISSN) ; Araghi, H ; Ghahari, M ; Faghihi Sani, M. A ; Sharif University of Technology
Springer Verlag
2016
Abstract
W-doped VO2 films have been synthesized via oxygen annealing of V–W–V (vanadium–tungsten–vanadium) multilayered films. The effects of middle layer’s thickness of V–W–V multilayered film on structure and properties of VOX–WOX–VOX ceramic thin films were investigated. The as-deposited V–W–V multilayered film showed amorphous-like structure when mixed structure of VO2 (M) and VO2 (B) was formed in VOX–WOX–VOX ceramic thin films. Tungsten content of VOX–WOX–VOX ceramic thin films increased with increasing middle layer’s thickness. With increasing middle layer’s thickness, room temperature square resistance (Rsq) of VOX–WOX–VOX ceramic thin films increased from 65 to 86 kΩ/sq. The VOX–WOX–VOX...
Determination of surface properties and elastic constants of FCC metals: A comparison among different EAM potentials in thin film and bulk scale
, Article Materials Research Express ; Volume 6, Issue 1 , 2019 ; 20531591 (ISSN) ; Yousefi, F. S ; Taghibakhshi, A ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Three independent elastic constants C 11, C 12, and C 44 were calculated and compared using available potentials of eight different metals with FCC crystal structure; Gold, Silver, Copper, Nickel, Platinum, Palladium, Aluminum and Lead. In order to calculate the elastic constants, the second derivative of the energy density of each system was calculated with respect to different directions of strains. Each set of the elastic constants of the metals in bulk scale was compared with experimental results, and the average relative error was for each was calculated and compared with other available potentials. Then, using the Voigt-Reuss-Hill method, approximated values for Young and shear moduli...
Fabrication of perovskite solar cells based on vacuum-assisted linear meniscus printing of MAPbI3
, Article Solar Energy Materials and Solar Cells ; Volume 191 , 2019 , Pages 148-156 ; 09270248 (ISSN) ; Abdollah zadeh, A ; Akbari, H. R ; Taghavinia, N ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Scale-up deposition methods in perovskite solar cell research, are mostly used under humidity environment outside the glove-box. Also, the as-printed absorbing layer before the post-annealing process is always wet. Thus, controlling the morphology and crystallization of perovskite thin-films in up-scaled deposition systems is difficult and strongly investigated by the researchers. In this work, we introduce an anti-solvent-free meniscus printing method in which, the absorbing perovskite film with optimal performance is achieved. To this end, we check the printing parameters to get to the optimized film characteristics. Also, a vacuum chamber (<100 Pa) is used for 30 s to remove the solvent...
High temperature NiTiHf shape memory thin films fabricated by simultaneous sputter deposition from elemental targets
, Article International Conference on Shape Memory and Superelastic Technologies, SMST-2006, Pacific Grove, CA, 7 May 2006 through 11 May 2006 ; 2008 , Pages 315-322 ; 9780871708625 (ISBN) ; Sadrnezhaad, .Kh ; Barber, Z. H ; Sharif University of Technology
2008
Abstract
NiTiHf thin films with varying hafnium contents up to 28.7at% were fabricated using simultaneous sputter deposition from separate Ni, Ti, and Hf targets onto unheated substrates. The required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; and post deposition annealing was performed at 550°C, slightly above their crystallization temperatures. The crystallization temperature of the films varied as a function of Hf concentration, and was as high as 520°C at a Hf content of 28.7at%. 2μm thick crystallized films with I0at% or greater Hf were martensitic at room temperature. DSC analysis demonstrated that above 10at%Hf additions...