The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
F Yakuphanoglu - One of the best experts on this subject based on the ideXlab platform.
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synthesis and electro optic properties of nanosized boron doped Cadmium Oxide thin films for solar cell applications
Solar Energy, 2011Co-Authors: F YakuphanogluAbstract:Abstract Boron doped CdO thin films were prepared by sol–gel dip coating technique. Atomic force microscopy results indicate that the boron doped CdO films have the nanostructure. The influence of the boron doping on the film growth is resulted in a change of grain size. The optical band gap of the CdO films was significantly changed by boron dopant. The refractive index dispersion of the films obeys the single oscillator model. The dispersion parameters, oscillator and dispersion energy were changed by boron dopant. The optical absorption results show that the optical band gap of the CdO film can be engineered over a wide range of 2.27–2.45 eV by introducing B dopant. For solar cell applications of the CdO film, a p-Si/1% B doped n-CdO heterojunction solar cell was fabricated and the solar cell shows the best values of open circuit voltage, V oc = 0.37 and short circuit current density, J sc = 0.81 mA/cm 2 under AM1.5 illumination, despite the fact that V oc and J sc are lower than those reported in the literature without using frontal grid contacts and or post-deposition annealing. It is evaluated that this work is useful as a basis search for synthesis of the nanosized-boron doped Cadmium Oxide thin films for solar cell applications and more competitive p-Si/n-CdO based solar cells.
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nanopowder synthesis of aluminum doped Cadmium Oxide via sol gel calcination processing
Journal of Alloys and Compounds, 2011Co-Authors: Cihat Aydin, F Yakuphanoglu, H M Elnasser, I S Yahia, M AksoyAbstract:Abstract The structural, optical and electrical properties of undoped and Al-doped CdO powder nanostructures prepared by sol–gel calcinations method have been investigated. X-ray diffraction (XRD) results revealed that pure and Al-doped CdO have the polycrystalline with face centered cubic (FCC) structure. The crystallite size for undoped and 5, 10, 15, 20% of Al-doped CdO samples were found to be 17.2, 15.9, 16.1, 16.3 and 16.8 nm, respectively. The optical band gap of the samples were determined from the diffused reflectance spectra and E g values for undoped and 5, 10, 15, 20% of Al-doped CdO samples were found to be 1.89, 2.07, 2.03, 2.07 and 2.12 eV, respectively. The electrical conductivities of pure and Al-doped CdO were measured in the temperature range (290–420 K) and their temperature dependence was analyzed according to Arrhenius relation. The electrical conductivity results indicate that the electrical conductivity mechanism is controlled by thermally activated processes. The results showed that sol–gel calcinations technique can be effectively used to produce undoped and doped nanopowders.
K K Chattopadhyay - One of the best experts on this subject based on the ideXlab platform.
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electrical and optical properties of al doped Cadmium Oxide thin films deposited by radio frequency magnetron sputtering
Solar Energy Materials and Solar Cells, 2007Co-Authors: Biswajit Saha, Sandhitsu R Das, K K ChattopadhyayAbstract:Abstract Cadmium Oxide thin films with different percentages of aluminum doping have been synthesized via radio frequency magnetron sputtering technique. Thin films were deposited on glass and silicon substrates with different percentages of aluminum at a substrate temperature of 573 K and pressure of 0.1 mbar in Ar+O 2 atmosphere. The deposited films were characterized by studying their structural, electrical and optical properties. The X-ray diffraction pattern revealed good crystallinity with preferred (1 1 1) orientation in the films. Aluminum doping in CdO thin films were confirmed by X-ray photoelectron spectroscopic studies and actual doping percentages were also measured from it. The optical band gap was found to decrease first and then increase with increasing percentages of aluminum concentrations. The electrical conductivity was found to increase with increase of aluminum doping concentration up to 5% but for higher doping concentration (>5%) the conductivity was found to decrease.
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synthesis and characterization of aluminum doped cdo thin films by sol gel process
Solar Energy Materials and Solar Cells, 2006Co-Authors: R Maity, K K ChattopadhyayAbstract:Aluminum-doped Cadmium Oxide (CdO:Al) thin films are deposited on glass substrates by the sol–gel dip-coating method, taking Cadmium acetate dihydrate as the precursor material. Aluminum nitrate has been taken as a source of Al-dopant. XRD pattern reveals the good crystallinity of CdO thin films. SEM micrograph showed the presence of faceted crystallites. Optical study shows 40–85% transparency with a bandgap value lying in the range 2.76–2.52 eV, depending upon the Al content in the films. Optimum percentage of Al was 5.22 for a maximum room temperature conductivity of 2.81×103 (Ω cm)−1. Hall measurement confirmed that the material is of n-type, with mobility and carrier concentrations lying in the range 413–14.7 cm2/V s, and 3.4×1019–8.11×1020 cm−3, when percentage of Al varies in the range 1.32–7.24.
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electrical and optical properties of highly conducting cdo f thin film deposited by sol gel dip coating technique
Solar Energy Materials and Solar Cells, 2004Co-Authors: P K Ghosh, R Maity, K K ChattopadhyayAbstract:Abstract Highly conducting fluorine-doped Cadmium Oxide (CdO:F) thin films were deposited by sol–gel dip coating technique on glass and Si substrates. F concentration in the films was varied from 2.0% to 13.8% as determined from energy dispersive X-ray analysis. X-ray diffraction pattern showed that the films were polycrystalline in nature. The optimum F concentration for obtaining maximum conductivity was found to be ∼9.7%. The corresponding electrical conductivity was found to be ∼1.088×10 4 S/cm and mobility ∼60.41 V/cm 2 . Analysis of UV-VIS-NIR spectrum of the film with F concentration ∼9.7% showed a direct band gap energy of 2.3 eV.
Vinod Kumar Gupta - One of the best experts on this subject based on the ideXlab platform.
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zno cdo nanocomposites for textile effluent degradation and electrochemical detection
Journal of Molecular Liquids, 2015Co-Authors: R. Saravanan, Vinod Kumar Gupta, V. Narayanan, Francisco Gracia, Mohammad Mansoob Khan, V. Poornima, A. StephenAbstract:Abstract In this report, the photocatalytic and electrochemical activity of ZnO and ZnO/CdO nanocomposites were determined. Pure ZnO and nanocomposite ZnO/CdO were prepared by a vapor to solid mechanism and were characterized by different physical and chemical techniques. The CdO-modified ZnO possessed high efficiency to degrade textile effluent. It also showed high efficiency of degradation, such as 98% for methylene blue and 93% for methyl orange. Cadmium Oxide (impurity) plays an important role in achieving zinc Oxide materials that exhibit UV to visible light degradation of textile effluent. Additionally, uric acid sensing performed to study the electrochemical activity revealed that ZnO/CdO (90:10) nanocomposite produced high anodic currents, and these results were in agreement with the cyclic voltammetry reports.
Wladek Walukiewicz - One of the best experts on this subject based on the ideXlab platform.
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Defects and properties of Cadmium Oxide based transparent conductors
Journal of Applied Physics, 2016Co-Authors: Douglas M. Detert, Guibin Chen, Wei Zhu, Chao Ping Liu, S. Grankowska, L. Hsu, Oscar D. Dubon, Wladek WalukiewiczAbstract:Transparent conductors play an increasingly important role in a number of semiconductor technologies. This paper reports on the defects and properties of Cadmium Oxide, a transparent conducting Oxide which can be potentially used for full spectrum photovoltaics. We carried out a systematic investigation on the effects of defects in CdO thin films undoped and intentionally doped with In and Ga under different deposition and annealing conditions. We found that at low growth temperatures ( 1 Ω cm due to...
Jon-paul Maria - One of the best experts on this subject based on the ideXlab platform.
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high harmonic generation from an epsilon near zero material
Nature Physics, 2019Co-Authors: Yuanmu Yang, Ting S. Luk, Jon-paul Maria, Michael B. Sinclair, Kyle P Kelley, Evan L Runnerstrom, Alejandro Manjavacas, Hanzhe Liu, Shambhu Ghimire, Igal BrenerAbstract:High-harmonic generation (HHG) is a signature optical phenomenon of strongly driven, nonlinear optical systems. Specifically, the understanding of the HHG process in rare gases has played a key role in the development of attosecond science1. Recently, HHG has also been reported in solids, providing novel opportunities such as controlling strong-field and attosecond processes in dense optical media down to the nanoscale2. Here, we report HHG from a low-loss, indium-doped Cadmium Oxide thin film by leveraging the epsilon-near-zero (ENZ) effect3–8, whereby the real part of the material’s permittivity in certain spectral ranges vanishes, as well as the associated large resonant enhancement of the driving laser field. We find that ENZ-assisted harmonics exhibit a pronounced spectral redshift as well as linewidth broadening, resulting from the photo induced electron heating and the consequent time-dependent ENZ wavelength of the material. Our results provide a new platform to study strong-field and ultrafast electron dynamics in ENZ materials, reveal new degrees of freedom for spectral and temporal control of HHG, and open up the possibilities of compact solid-state attosecond light sources. High harmonics are generated from a thin film by leveraging the epsilon-near-zero effect. These kinds of harmonic are found to exhibit a pronounced spectral redshift as well as linewidth broadening caused by the time-dependency of this effect.
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polaritonic hybrid epsilon near zero modes engineering strong optoelectronic coupling and dispersion in doped Cadmium Oxide bilayers conference presentation
Photonic and Phononic Properties of Engineered Nanostructures IX, 2019Co-Authors: Thomas G Folland, Jon-paul Maria, Evan L Runnerstrom, Kyle Kelly, Nader Engheta, Joshua D CaldwellAbstract:Polaritonic materials that support epsilon-near-zero (ENZ) modes offer the opportunity to design light-matter interactions at the nanoscale through phenomena like resonant perfect absorption and extreme sub-wavelength light concentration. To date, the utility of ENZ modes is limited in propagating polaritonic systems by a relatively flat spectral dispersion, which gives ENZ modes small group velocities and therefore short propagation lengths. Here we overcome this constraint by coupling ENZ modes to surface plasmon polariton (SPP) modes in doped Cadmium Oxide ENZ-on-SPP bilayers. What results is a strongly coupled hybrid mode, characterized by strong anti-crossing and a large spectral splitting on the order of 1/3 of the mode frequency. The resonant frequencies, dispersion, and coupling of these polaritonic-hybrid-epsilon-near-zero (PH-ENZ) modes are controlled by tailoring the modal oscillator strength and the ENZ-SPP spectral overlap. As Cadmium Oxide supports polaritons over a wide range of carrier concentrations without excessive losses, strong coupling effects can potentially be utilized for actively tunable strong coupling at the nanoscale. PH-ENZ modes ultimately leverage the most desirable characteristics of both ENZ and SPP modes through simultaneous strong interior field confinement and mode propagation. As a result, this system could see applications in sub-diffraction modulators using carrier injection schemes, or narrow linewidth thermal emitters working in the 3-5µm spectral window.
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polaritonic hybrid epsilon near zero modes beating the plasmonic confinement vs propagation length trade off with doped Cadmium Oxide bilayers
Nano Letters, 2019Co-Authors: Evan L Runnerstrom, Jon-paul Maria, Kyle P Kelley, Thomas G Folland, Nader Engheta, Joshua D Caldwell, Ryan J NolenAbstract:Polaritonic materials that support epsilon-near-zero (ENZ) modes offer the opportunity to design light–matter interactions at the nanoscale through extreme subwavelength light confinement, producin...
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epsilon near zero modes and surface plasmon resonance in fluorine doped Cadmium Oxide thin films
ACS Photonics, 2017Co-Authors: Evan L Runnerstrom, Edward Sachet, Christopher T Shelton, Kyle P Kelley, Jon-paul MariaAbstract:In this report we demonstrate fluorine-doped CdO as a model infrared plasmonic material by virtue of its tunable carrier density, high mobility, and intense extreme-subwavelength plasmon–polariton coupling. Carrier concentrations ranging from 1019 to 1020 cm–3, with electron mobility values as high as 473 cm2/V·s, are readily achieved in epitaxial CdO films over a thickness range spanning 50 to 500 nm. Carrier concentration is achieved by reactive sputtering in an Ar/O2 atmosphere with trace quantities of CF4. Infrared reflectometry measurements demonstrate the possibility of near-perfect plasmonic absorption through the entire mid-IR spectral range. A companion set of reflectivity simulations are used to predict, understand, and optimize the epsilon-near-zero plasmonic modes. In the context of other transparent conductors, CdO exhibits substantially higher electron mobility values and thus sharp and tunable absorption features. This highlights the utility of high-mobility transparent conducting Oxides as...
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Femtosecond optical polarization switching using a Cadmium Oxide-based perfect absorber
Nature Photonics, 2017Co-Authors: Yuanmu Yang, Edward Sachet, Kyle Kelley, Salvatore Campione, Ting S. Luk, Jon-paul Maria, Michael B. Sinclair, Igal BrenerAbstract:Ultrafast control of the polarization state of light may enable a plethora of applications in optics, chemistry and biology. However, conventional polarizing elements, such as polarizers and waveplates, are either static or possess only gigahertz switching speeds. Here, with the aid of high-mobility indium-doped Cadmium Oxide (CdO) as the gateway plasmonic material, we realize a high-quality factor Berreman-type perfect absorber at a wavelength of 2.08 μm. On sub-bandgap optical pumping, the perfect absorption resonance strongly redshifts because of the transient increase of the ensemble-averaged effective electron mass of CdO, which leads to an absolute change in the p -polarized reflectance from 1.0 to 86.3%. By combining the exceedingly high modulation depth with the polarization selectivity of the perfect absorber, we experimentally demonstrate a reflective polarizer with a polarization extinction ratio of 91 that can be switched on and off within 800 fs. Indium-doped Cadmium Oxide performs polarization switching on a subpicosecond timescale.
