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André Savall - One of the best experts on this subject based on the ideXlab platform.
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effects of Individual Layer thickness on the microstructure and optoelectronic properties of sol gel derived zinc oxide thin films
Journal of the American Ceramic Society, 2008Co-Authors: Noureddine Belhadj Tahar, Radhouane Bel Hadj Tahar, Abdelhamid Ben Salah, André SavallAbstract:Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol–gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The Individual Layer thickness for Layer-by-Layer homoepitaxy growth that resulted in columnar grains was <20 nm. The grain columns are grown through the entire film with a nearly unchanged lateral dimension through the full film thickness. The columnar ZnO grains are c-axis oriented perpendicular to the interface and possess a polycrystalline structure. Optical transmittance up to 90% in the visible range and electrical resistivity as low as 6.8 × 10−3·Ω·cm were obtained under optimal deposition conditions.
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Effects of Individual Layer Thickness on the Microstructure and Optoelectronic Properties of Sol–Gel‐Derived Zinc Oxide Thin Films
Journal of the American Ceramic Society, 2008Co-Authors: Noureddine Belhadj Tahar, Radhouane Bel Hadj Tahar, Abdelhamid Ben Salah, André SavallAbstract:Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol–gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The Individual Layer thickness for Layer-by-Layer homoepitaxy growth that resulted in columnar grains was
Krishnan Narasimhan - One of the best experts on this subject based on the ideXlab platform.
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synthesis of titanium carbide chromium carbide multiLayers by the co evaporation of multiple ingots by electron beam physical vapor deposition
Surface & Coatings Technology, 2002Co-Authors: Douglas E Wolfe, Jogender Singh, Krishnan NarasimhanAbstract:Abstract Titanium carbide and chromium carbide multiLayer coatings with varying Individual Layer thicknesses were synthesized by the co-evaporation of titanium, chromium, and carbon (through tungsten) ingots by electron beam-physical vapor deposition. The adhesion of the multiLayer coatings was found to be greater than 50 N. The hardness of the titanium carbide/chromium carbide multiLayer coatings was found to increase from 1302 VHN 0.050 to 2052 VHN 0.050 by decreasing the thickness of the Individual Layer from 1.2 to 0.1 μm. In addition, the average grain diameter was also found to decrease from 3.315 to 0.356 μm by decreasing the thickness of the Individual Layers. The fracture toughness of the TiC/CrC multiLayer coatings decreased from 4.179 to 1.411 MPa-m 1 2 with decreasing Layer thickness. Lastly, the amount of compressive stress in both the TiC and CrC Layers within the multiLayer coating was found to decrease with decreasing Individual Layer thickness. The samples were characterized by various techniques including Vicker's hardness, X-ray diffraction, scanning electron microscopy, scratch testing and fracture toughness, with the results being presented.
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Synthesis of titanium carbide/chromium carbide multiLayers by the co-evaporation of multiple ingots by electron beam physical vapor deposition
Surface & Coatings Technology, 2002Co-Authors: Douglas E Wolfe, Jogender Singh, Krishnan NarasimhanAbstract:Abstract Titanium carbide and chromium carbide multiLayer coatings with varying Individual Layer thicknesses were synthesized by the co-evaporation of titanium, chromium, and carbon (through tungsten) ingots by electron beam-physical vapor deposition. The adhesion of the multiLayer coatings was found to be greater than 50 N. The hardness of the titanium carbide/chromium carbide multiLayer coatings was found to increase from 1302 VHN 0.050 to 2052 VHN 0.050 by decreasing the thickness of the Individual Layer from 1.2 to 0.1 μm. In addition, the average grain diameter was also found to decrease from 3.315 to 0.356 μm by decreasing the thickness of the Individual Layers. The fracture toughness of the TiC/CrC multiLayer coatings decreased from 4.179 to 1.411 MPa-m 1 2 with decreasing Layer thickness. Lastly, the amount of compressive stress in both the TiC and CrC Layers within the multiLayer coating was found to decrease with decreasing Individual Layer thickness. The samples were characterized by various techniques including Vicker's hardness, X-ray diffraction, scanning electron microscopy, scratch testing and fracture toughness, with the results being presented.
Peter Schaaf - One of the best experts on this subject based on the ideXlab platform.
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Solid-state dewetting of Au–Ni bi-Layer films mediated through Individual Layer thickness and stacking sequence
Applied Surface Science, 2018Co-Authors: Andreas Herz, Felix Theska, Diana Rossberg, Thomas Kups, Dong Wang, Peter SchaafAbstract:Abstract In the present work, the solid-state dewetting of Au–Ni bi-Layer thin films deposited on SiO2/Si is systematically studied with respect to Individual Layer thickness and stacking sequence. For this purpose, a rapid heat treatment at medium temperatures is applied in order to examine void formation at the early stages of the dewetting. Compositional variations are realized by changing the thickness ratio of the bi-Layer films, while the total thickness is maintained at 20 nm throughout the study. In the event of Au/Ni films annealed at 500 °C, crystal voids exposing the substrate are missing regardless of chemical composition. In reverse order, the number of voids per unit area in two-phase Au–Ni thin films is found to be governed by the amount of Au-rich material. At higher temperatures up to 650 °C, a decreased probability of nucleation comes at the expense of a major portion of cavities, resulting in the formation of bubbles in 15 nm Ni/5 nm Au bi-Layers. Film buckling predominantly occurred at phase boundaries crossing the bubbles.
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Layer thickness effect on fracture behavior of Al/Si 3 N 4 multiLayer on Si substrate under three-point bending
Applied Surface Science, 2018Co-Authors: M. Wang, Dong Wang, Peter SchaafAbstract:Abstract The fracture behavior of multiLayers in the nanometer thickness range has attracted an increased attention due to microelectronics and high-speed technologies. In this work, Al/Si3N4 multiLayers fabricated by magnetron sputtering on the silicon substrate were subjected to three-point bend testing. It was investigated that the fracture behavior of Al/Si3N4 multiLayers with different Individual Layer thickness λ (50, 100, 250 nm) but with the same total thickness (1.0 µm). There is a significant Layer thickness effect on the fracture behavior of the whole multiLayer-substrate system: when the Individual Layer thickness is large (250 nm), the failure of the whole system was dominated by the fracture of the substrate, while the failure of the whole system was dominated by the fracture of the multiLayer with smaller Individual Layer thickness (50 nm). This effect is clearly obvious, although the total thickness of the multiLayer is very small compared with that of the substrate. As the Individual Layer thickness decreased from 250 nm to 50 nm, the fracture strain on the Al/Si3N4 multiLayer decreased from 0.073% to 0.026%.
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solid state dewetting of single and biLayer au w thin films unraveling the role of Individual Layer thickness stacking sequence and oxidation on morphology evolution
AIP Advances, 2016Co-Authors: Andreas Herz, Felix Theska, Thomas Kups, Dong Wang, Anna Franz, Martin Hentschel, Peter SchaafAbstract:Self-assembly of ultrathin Au, W, and Au-W biLayer thin films is investigated using a rapid thermal annealing technique in an inert ambient. The solid-state dewetting of Aufilms is briefly revisited in order to emphasize the role of initial film thickness. W films deposited onto SiO2 evolve into needle-like nanocrystals rather than forming particle-like agglomerates upon annealing at elevated temperatures. Transmission electron microscopy reveals that such nanocrystals actually consist of tungsten (VI) oxide (WO3) which is related to an anisotropic oxide crystal growth out of the thin film. The evolution of W films is highly sensitive to the presence of any residual oxygen. Combination of both the dewetting of Au and the oxide crystal growth of WO3 is realized by using various biLayer film configurations of the immiscible Au and W. At low temperature, Au dewetting is initiated while oxide crystal growth is still suppressed. Depending on the stacking sequence of the Au-W biLayer thin film, W acts either as a substrate or as a passivation Layer for the dewetting of Au. Being the ground Layer, W changes the wettability of Au which clearly modifies its initial state for the dewetting. Being the top Layer, W prevents Au from dewetting regardless of Aufilm thickness. Moreover, regular pattern formation of Au-WO3 nanoparticles is observed at high temperature demonstrating how biLayer thin film dewetting can create unique nanostructure arrangements.
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Size effect on the mechanical behavior of Al/Si multiLayers deposited on Kapton substrate
Journal of Materials Science: Materials in Electronics, 2015Co-Authors: Ming Wang, Dong Wang, Peter SchaafAbstract:The mechanical properties of multiLayers with Individual Layer thickness in the nanometers range have attracted an increased attention due to the important implication on the reliability of microelectronic devices. In this work, Al/Si multiLayers with different Individual Layer thickness t (25, 100, 250 nm) but with the same total thickness (1.0 µm), were fabricated by magnetron sputtering onto Kapton substrates, and then were studied by tensile testing with maximal strain of e max = 10 %. It is found the thinner the Individual Layer is, it is more difficult to generate the plastic shear deformation. And the tensile strength increases with decreasing Layer thickness. Many buckling damages appeared on the surface of Al/Si multiLayer under the compressive stress vertical to the tensile direction. The buckling becomes more and more absent when the Individual Layer thickness decreases from sub-micron scale to nanometer scale.
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Deformation behavior of Au/Ti multiLayers under indentation
Journal of Materials Science: Materials in Electronics, 2011Co-Authors: Dong Wang, Thomas Kups, Jens Schawohl, Peter SchaafAbstract:Au/Ti multiLayers with Individual Layer thicknesses of 25 nm and 250 nm were deformed by indentation with a Vickers indenter. The deformation behavior changes from delamination-controlled for the multiLayer with an Individual Layer thickness of 250 nm to shear banding for the multiLayer with an Individual Layer thickness of 25 nm. The length-scale effect on delamination resistance is discussed and it is found that the delamination resistance of the Au/Ti interfaces increases with decreasing Layer thickness.
Noureddine Belhadj Tahar - One of the best experts on this subject based on the ideXlab platform.
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effects of Individual Layer thickness on the microstructure and optoelectronic properties of sol gel derived zinc oxide thin films
Journal of the American Ceramic Society, 2008Co-Authors: Noureddine Belhadj Tahar, Radhouane Bel Hadj Tahar, Abdelhamid Ben Salah, André SavallAbstract:Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol–gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The Individual Layer thickness for Layer-by-Layer homoepitaxy growth that resulted in columnar grains was <20 nm. The grain columns are grown through the entire film with a nearly unchanged lateral dimension through the full film thickness. The columnar ZnO grains are c-axis oriented perpendicular to the interface and possess a polycrystalline structure. Optical transmittance up to 90% in the visible range and electrical resistivity as low as 6.8 × 10−3·Ω·cm were obtained under optimal deposition conditions.
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Effects of Individual Layer Thickness on the Microstructure and Optoelectronic Properties of Sol–Gel‐Derived Zinc Oxide Thin Films
Journal of the American Ceramic Society, 2008Co-Authors: Noureddine Belhadj Tahar, Radhouane Bel Hadj Tahar, Abdelhamid Ben Salah, André SavallAbstract:Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol–gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The Individual Layer thickness for Layer-by-Layer homoepitaxy growth that resulted in columnar grains was
Douglas E Wolfe - One of the best experts on this subject based on the ideXlab platform.
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synthesis of titanium carbide chromium carbide multiLayers by the co evaporation of multiple ingots by electron beam physical vapor deposition
Surface & Coatings Technology, 2002Co-Authors: Douglas E Wolfe, Jogender Singh, Krishnan NarasimhanAbstract:Abstract Titanium carbide and chromium carbide multiLayer coatings with varying Individual Layer thicknesses were synthesized by the co-evaporation of titanium, chromium, and carbon (through tungsten) ingots by electron beam-physical vapor deposition. The adhesion of the multiLayer coatings was found to be greater than 50 N. The hardness of the titanium carbide/chromium carbide multiLayer coatings was found to increase from 1302 VHN 0.050 to 2052 VHN 0.050 by decreasing the thickness of the Individual Layer from 1.2 to 0.1 μm. In addition, the average grain diameter was also found to decrease from 3.315 to 0.356 μm by decreasing the thickness of the Individual Layers. The fracture toughness of the TiC/CrC multiLayer coatings decreased from 4.179 to 1.411 MPa-m 1 2 with decreasing Layer thickness. Lastly, the amount of compressive stress in both the TiC and CrC Layers within the multiLayer coating was found to decrease with decreasing Individual Layer thickness. The samples were characterized by various techniques including Vicker's hardness, X-ray diffraction, scanning electron microscopy, scratch testing and fracture toughness, with the results being presented.
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Synthesis of titanium carbide/chromium carbide multiLayers by the co-evaporation of multiple ingots by electron beam physical vapor deposition
Surface & Coatings Technology, 2002Co-Authors: Douglas E Wolfe, Jogender Singh, Krishnan NarasimhanAbstract:Abstract Titanium carbide and chromium carbide multiLayer coatings with varying Individual Layer thicknesses were synthesized by the co-evaporation of titanium, chromium, and carbon (through tungsten) ingots by electron beam-physical vapor deposition. The adhesion of the multiLayer coatings was found to be greater than 50 N. The hardness of the titanium carbide/chromium carbide multiLayer coatings was found to increase from 1302 VHN 0.050 to 2052 VHN 0.050 by decreasing the thickness of the Individual Layer from 1.2 to 0.1 μm. In addition, the average grain diameter was also found to decrease from 3.315 to 0.356 μm by decreasing the thickness of the Individual Layers. The fracture toughness of the TiC/CrC multiLayer coatings decreased from 4.179 to 1.411 MPa-m 1 2 with decreasing Layer thickness. Lastly, the amount of compressive stress in both the TiC and CrC Layers within the multiLayer coating was found to decrease with decreasing Individual Layer thickness. The samples were characterized by various techniques including Vicker's hardness, X-ray diffraction, scanning electron microscopy, scratch testing and fracture toughness, with the results being presented.