Nickel oxide (NiO) nanostructures were deposited on Si (100), potassium bromide (KBr), and glass ... more Nickel oxide (NiO) nanostructures were deposited on Si (100), potassium bromide (KBr), and glass slide substrates at room temperature by the evaporation technique. The prepared samples were annealed at temperatures of 400 • C and 600 • C in air atmosphere. The structure, morphology, crystalline phase, optical properties, and chemical bonding of nanocrystalline nickel oxide were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible absorption spectrum, and FT-IR spectroscopy. XRD results and SEM images showed that nickel oxide nanoparticles have preferred orientation with uniform size distribution. The as-deposited films showed preferred orientation (texture) growth. As the films were annealed, the crystallites were agglomerated to form bigger particles. Optical properties were identified by measuring transmittance using a UV-Vis spectrophotometer. Optical constants such as the refractive index n, the extinction coefficient k, and the films' thickness and roughness were calculated from transmittance data using a reverse engineering method. As the sample annealed, the ad-atom surface mobility increased, and smaller crystallites agglomerated to form bigger ones.
IEEE Transactions on Wireless Communications, 2021
With the ease of deployment, capabilities of evading the jammers and obscuring their existence, u... more With the ease of deployment, capabilities of evading the jammers and obscuring their existence, unmanned aerial vehicles (UAVs) are one of the most suitable candidates to perform surveillance. There exists a body of literature in which the inspectors follow a deterministic trajectory to conduct surveillance, which results in a predictable environment for malicious entities. Thus, introducing randomness to the surveillance is of particular interest. In this work, we propose a novel framework for stochastic UAV-assisted surveillance that i) inherently considers the battery constraints of the UAVs, ii) proposes random moving patterns modeled via random walks, and iii) adds another degree of randomness to the system via considering probabilistic inspections. We formulate the problem of interest, i.e., obtaining the energy-efficient random walk and inspection policies of the UAVs subject to probabilistic constraints on inspection criteria of the sites and battery consumption of the UAVs, which turns out to be signomial programming that is highly non-convex. To solve it, we propose a centralized and a distributed algorithm along with their performance guarantee. This work contributes to both UAV-assisted surveillance and classic random walk literature by designing random walks with random inspection policies on weighted graphs with energy limited random walkers.
A Novel Optimization Framework to Improve the Computational Cost of Muscle Activation Prediction for a Neuromusculoskeletal System
Neural Computation
The high computational cost (CC) of neuromusculoskeletal modeling is usually considered a serious... more The high computational cost (CC) of neuromusculoskeletal modeling is usually considered a serious barrier in clinical applications. Different approaches have been developed to lessen CC and amplify the accuracy of muscle activation prediction based on forward and inverse analyses by applying different optimization algorithms. This study is aimed at proposing two novel approaches, inverse muscular dynamics with inequality constraints (IMDIC) and inverse-forward muscular dynamics with inequality constraints (IFMDIC), not only to reduce CC but also to amend the computational errors compared to the well-known approach of extended inverse dynamics (EID). To do that, the equality constraints of optimization problem, which are computationally tough to satisfy, are replaced by inequality constraints, which are easier to satisfy. To verify the practical application of the proposed approaches, the muscle activations of the lower limbs during the half of a gait cycle are quantified. The simula...
Effect of Deposition time On Optical And Structural Characteristics of Zinc Oxid Nanostructures Grown By Carbothermal Reduction Technique On Copper Nanosheet
ZnO micro-/nanostructures were synthesized by the carbothermal reduction–chemical vapour transpor... more ZnO micro-/nanostructures were synthesized by the carbothermal reduction–chemical vapour transport method. This work is focused on the effect of the substrate temperature and Cu catalyst layer on the shape and geometry of ZnO micro-/nanostructures. The thermally oxidized Cu template affects the structure, chemical identity, optical and photoluminescence properties of the ZnO micro-/nanostructure and results in a CuO x /ZnO heterostructure. SEM studies give a direct evidence of the role of deposition temperature and Cu catalyst in the formation of a stable hemisphere based wire, a comb-like cantilever, a javelin-like tetrapod, a spherical and polyhedral cage of ZnO. XRD and Raman measurements confirm a hexagonal wurtzite structure of the ZnO micro-/nanostructure. The absorption edge of the ZnO/CuO x heterostructure is redshifted in comparison to the pure ZnO structure. PL studies indicate that the UV emission can be suppressed significantly while the green emission is enhanced due to...
Charge transfer plasmon coupled surface photosensing in ZnO nanorods–Au array hetero-nanostructures
Optics and Lasers in Engineering
Abstract Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method ... more Abstract Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method on seeded substrates at low temperature. Gold nanosheet has been deposited by DC magnetron sputtering on the surrounding of the ZnO NRs array at glancing angle, thus creating a three-dimensionally (3D) plasmonic hetero-nanostructure (HNS). The localized surface plasmon resonance (LSPR) is tuned and blue-shifted as the thickness of the gold nanosheet increased. The efficient surface plasmon (SP) excitation, and charge transfer plasmon through tunneling transport and junction conductance elevates the locally electromagnetic field and subsequently enhances surface Raman scattering in ZnO NRs-Au array HNS. An enhanced factor (EF) of 500 can be obtained for the surface enhancement Raman scattering (SERS) response for ZnO NRs-Au array HNS. Photoluminescence spectrum shows Au- mediated blue emission enhancement. The ZnO NRs–Au HNSs show high nonlinear refractive index and nonlinear optical absorption coefficient around 10−5 cm2/W and 1 cm/W, respectively. The ZnO NRs-Au array HNS can provide the figures of merit w = 209.83 and t = 0.59 for the optical switching devices. Photosensitivity and photocatalytic activity are elevated in ZnO NRs-Au array HNS. The ZnO NRs-Au array HNS shows maximal photocurrent enhancement of 69.38% in comparison to the bare ZnO NRs array.
A logical NAND and NOR gate was simulated using bistability behavior in nonlinear medium of Fabry... more A logical NAND and NOR gate was simulated using bistability behavior in nonlinear medium of Fabry-Perot cavity based on the inverse trend of output intensity vs. input intensity. The gate was optimised relative to different cavity parameters, sharp edges between the ON and OFF modes and threshold switching intensity. The real and imaginary parts of the refractive index of the nonlinear medium were utilised to compute numerical results. Finally, gate speed was calculated to be 9.2 Gb/s.
Photoactivity and Light Harvesting in ZnO Nanorods Array / Au/ CuS Heterostructure
Surface Innovations
Zinc oxide (ZnO) nanorod arrays (NRs)/gold (Au)/copper sulfide (CuS) heterostructures were grown ... more Zinc oxide (ZnO) nanorod arrays (NRs)/gold (Au)/copper sulfide (CuS) heterostructures were grown by way of a low-temperature chemical approach, magnetron sputtering deposition and the successive ionic layer absorption and reaction route. The structural characteristics, morphological characteristics, elemental composition, current–voltage characteristics, ultraviolet–visible–near-infrared absorption and photocatalytic and photoelectrochemical properties of the ternary zinc oxide NR/gold/copper sulfide heterostructures were studied. The photocatalytic efficiency of the zinc oxide NRs/gold/copper sulfide heterostructures was higher than that of their zinc oxide NRs/copper sulfide counterparts. The zinc oxide NRs/gold/copper sulfide heterostructures were visible-light-photosensitive due to the lower bandgap of copper sulfide and localized surface plasmon resonance excitation of gold. The Schottky junction can motivate the photogenerated electron–hole to separate and transfer in opposite...
Rectifying Behaviour and Photocatalytic Activity in ZnO Nanorods Array/Ag/CuSe Heterostructure
Journal of Cluster Science
Ag incorporated vertically aligned ZnO nanorods array/CuSe thin film (ZnO NRs/CuSe TF) have been ... more Ag incorporated vertically aligned ZnO nanorods array/CuSe thin film (ZnO NRs/CuSe TF) have been fabricated via a solution route, thermal evaporation and magnetron sputtering process. Ternary ZnO nanorods/Ag/CuSe heterostructure was studied by X-ray diffractometry, field emission-scanning electron microscopy/energy dispersive X ray spectroscopy, current–voltage measurement and a UV–Vis–near IR spectrophotometer. The photocatalytic performance was estimated by the degradation of Rhodamine B solution under UV–Vis light irradiation. The photocatalytic efficiency of the ZnO NRs/Ag/CuSe heterostructure is higher than that of ZnO NRs/Ag and ZnO NRs/CuSe counterparts due to the robust effects of the three functional components coupling. The localized surface plasmon resonance and two Schottky junctions (e.g. Ag/ZnO and Ag/CuSe) motivates photogenerated electron–hole separation and transfer. This work presents an artificial manipulated system to enhance light harvesting, efficient charge separation and transfer, and low recombination rate in solar energy conversion.
Hetero plasmonic 2D and 3D ZnO/Ag nanostructures: electrical and photocatalytic applications
Journal of Materials Science: Materials in Electronics
ZnO thin films (TFs) and nanorods (NRs) array have been synthesized by RF magnetron sputtering an... more ZnO thin films (TFs) and nanorods (NRs) array have been synthesized by RF magnetron sputtering and low temperature wet chemical method, respectively. It is followed by deposition of Ag nanosheet using DC magnetron sputtering, which forms 2D and 3D ZnO/Ag heterointerfaces. This work devotes the significant of thickness, annealing and shape of ZnO–Ag heterojunction on its characteristics. A successful fabrication of ZnO–Ag heterostructure was presented to improve (modify) the conductivity and optical absorption. UV–Vis near IR absorption spectroscopy revealed higher absorption efficiency in the visible region for Ag–ZnO thin film rather than in pure ZnO. The optical response of ZnO–Ag composite based on Gans theory indicates surface plasmon resonance behavior as well in nonspheriod (oblate) Ag nanoislands. The transport behavior of FTO/Ag/ZnO NRs/Cu heterojunction could be useful in variable resistor (varistor). Current voltage characteristic of Ag/ZnO NRs/FTO shows good Schottky behavior. The predicted Schottky barrier height of 1 V was obtained which is not far from the theoretical Schottky–Mott value of 0.8 V. Photocatalytic degradation of Rhodamine B (RhB) was used to evaluate the activity of ZnO NRs/Ag heterostructure. ZnO NRs/Ag heterostructure depicts the best photocatalytic activity due to electronic and plasmonic coupling.
Heteroepitaxial ZnO/CuO thin film and nanorods array: photoconductivity and field emission effect
Journal of Materials Science: Materials in Electronics
ZnO thin film and nanorods array have been synthesized by RF magnetron sputtering and low tempera... more ZnO thin film and nanorods array have been synthesized by RF magnetron sputtering and low temperature wet chemical method, respectively. It is followed by deposition of Cu nanosheet using DC magnetron sputtering, which was oxidized subsequently to form 2D and 3D ZnO/CuO heterointerfaces. A successful fabrication of heteroepitaxial ZnO–CuO thin film was presented to improve the interface quality, crystallinity and conformal characteristic of CuO sheet. ZnO/CuO thin film revealed higher absorption efficiency in the visible region in comparison to pure ZnO. The rectifying behavior of n-ZnO/p-CuO junction could be useful in photoactive and photoconductive devices, while the uni-polar transport of p-CuO/n-ZnO thin film is beneficial for optical switching. This photoactivity attributed to extended light absorption and effective transfer of photogenerated carriers. The as-synthesized ZnO–Cu composite was determined to be a hierarchical heterostructure consisting of ZnO nanorods and Cu nanosheets with intimate hetero-interfaces. The formation of n+-Cu/n-ZnO heterointerface cause to electrostatic field which facilitates electron emission.
The role of nitrogen pressure on characteristics of reactively sputter deposited (Ti,Cu)N nanocrystalline thin films
(Ti,Cu)N thin films were deposited on Si (111), glass slide, quartz substrates using reactive DC ... more (Ti,Cu)N thin films were deposited on Si (111), glass slide, quartz substrates using reactive DC magnetron sputtering in molecular nitrogen ambient. The effect of different nitrogen pressure on the characteristic of (Ti,Cu)N films was examined. Structural analysis of the films was identified by X- ray diffraction (XRD) technique. As nitrogen pressure increased, film structure changes from random oriented growth to preferred ones. Lattice constant expansion shows that Ti soluted in Cu3N structure. Surface morphology and chemical composition of the films were studied by scanning electron microscope/ energy dispersive X- ray spectroscopy (SEM/EDX). At higher nitrogen pressure, films have clear nano-metric grain boundaries. The films were aggregated as spherical grains. Atomic titanium to copper (Ti:Cu) ratio of (Ti,Cu)N films was less than that of original target. Optical study was performed by Vis- near IR transmittance spectroscopy. Film thickness and absorption coefficient were extr...
Effect of nitrogen partial pressure on reactive magnetron sputtering from Ti13Cu87 metalloid target: simulation of chemical composition
Ukrainian Journal of Physics
Ti13Cu87 sintered composite target was reactively sputtered at Ar- N2 gas mixtures, and sputtered... more Ti13Cu87 sintered composite target was reactively sputtered at Ar- N2 gas mixtures, and sputtered species were deposited on Si (111) substrates. In this study, the pressure-dependent target mode variation of a Ti13Cu87–N2 system was investigated by measuring the N2 partial pressure, deposition rate, target voltage, and Ti and Cu concentration for various reactive N2 gas flow ratios. The Ti13Cu87 target surface begins to be nitrided with increasing N2 flow ratio. It is considered caused by the absorption and implantation of N2 gas on the Ti13Cu87 target surface. Hence, deposition rate was reduced due to lower sputtering yield and more scattering for mass transport between target- substrate spacing. Secondary electron emission yield from nitrided target surface is further than that of unnitrided target surface. Therefore, at constant sputtering power, target voltage decreased as the N2 partial pressure increased. By means of TRIM.SP Monte-Carlo simulation, the particle reflection coef...
Nickel oxide (NiO) nanostructures were deposited on Si (100), potassium bromide (KBr), and glass ... more Nickel oxide (NiO) nanostructures were deposited on Si (100), potassium bromide (KBr), and glass slide substrates at room temperature by the evaporation technique. The prepared samples were annealed at temperatures of 400 • C and 600 • C in air atmosphere. The structure, morphology, crystalline phase, optical properties, and chemical bonding of nanocrystalline nickel oxide were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible absorption spectrum, and FT-IR spectroscopy. XRD results and SEM images showed that nickel oxide nanoparticles have preferred orientation with uniform size distribution. The as-deposited films showed preferred orientation (texture) growth. As the films were annealed, the crystallites were agglomerated to form bigger particles. Optical properties were identified by measuring transmittance using a UV-Vis spectrophotometer. Optical constants such as the refractive index n, the extinction coefficient k, and the films' thickness and roughness were calculated from transmittance data using a reverse engineering method. As the sample annealed, the ad-atom surface mobility increased, and smaller crystallites agglomerated to form bigger ones.
IEEE Transactions on Wireless Communications, 2021
With the ease of deployment, capabilities of evading the jammers and obscuring their existence, u... more With the ease of deployment, capabilities of evading the jammers and obscuring their existence, unmanned aerial vehicles (UAVs) are one of the most suitable candidates to perform surveillance. There exists a body of literature in which the inspectors follow a deterministic trajectory to conduct surveillance, which results in a predictable environment for malicious entities. Thus, introducing randomness to the surveillance is of particular interest. In this work, we propose a novel framework for stochastic UAV-assisted surveillance that i) inherently considers the battery constraints of the UAVs, ii) proposes random moving patterns modeled via random walks, and iii) adds another degree of randomness to the system via considering probabilistic inspections. We formulate the problem of interest, i.e., obtaining the energy-efficient random walk and inspection policies of the UAVs subject to probabilistic constraints on inspection criteria of the sites and battery consumption of the UAVs, which turns out to be signomial programming that is highly non-convex. To solve it, we propose a centralized and a distributed algorithm along with their performance guarantee. This work contributes to both UAV-assisted surveillance and classic random walk literature by designing random walks with random inspection policies on weighted graphs with energy limited random walkers.
A Novel Optimization Framework to Improve the Computational Cost of Muscle Activation Prediction for a Neuromusculoskeletal System
Neural Computation
The high computational cost (CC) of neuromusculoskeletal modeling is usually considered a serious... more The high computational cost (CC) of neuromusculoskeletal modeling is usually considered a serious barrier in clinical applications. Different approaches have been developed to lessen CC and amplify the accuracy of muscle activation prediction based on forward and inverse analyses by applying different optimization algorithms. This study is aimed at proposing two novel approaches, inverse muscular dynamics with inequality constraints (IMDIC) and inverse-forward muscular dynamics with inequality constraints (IFMDIC), not only to reduce CC but also to amend the computational errors compared to the well-known approach of extended inverse dynamics (EID). To do that, the equality constraints of optimization problem, which are computationally tough to satisfy, are replaced by inequality constraints, which are easier to satisfy. To verify the practical application of the proposed approaches, the muscle activations of the lower limbs during the half of a gait cycle are quantified. The simula...
Effect of Deposition time On Optical And Structural Characteristics of Zinc Oxid Nanostructures Grown By Carbothermal Reduction Technique On Copper Nanosheet
ZnO micro-/nanostructures were synthesized by the carbothermal reduction–chemical vapour transpor... more ZnO micro-/nanostructures were synthesized by the carbothermal reduction–chemical vapour transport method. This work is focused on the effect of the substrate temperature and Cu catalyst layer on the shape and geometry of ZnO micro-/nanostructures. The thermally oxidized Cu template affects the structure, chemical identity, optical and photoluminescence properties of the ZnO micro-/nanostructure and results in a CuO x /ZnO heterostructure. SEM studies give a direct evidence of the role of deposition temperature and Cu catalyst in the formation of a stable hemisphere based wire, a comb-like cantilever, a javelin-like tetrapod, a spherical and polyhedral cage of ZnO. XRD and Raman measurements confirm a hexagonal wurtzite structure of the ZnO micro-/nanostructure. The absorption edge of the ZnO/CuO x heterostructure is redshifted in comparison to the pure ZnO structure. PL studies indicate that the UV emission can be suppressed significantly while the green emission is enhanced due to...
Charge transfer plasmon coupled surface photosensing in ZnO nanorods–Au array hetero-nanostructures
Optics and Lasers in Engineering
Abstract Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method ... more Abstract Well-aligned zinc oxide nanorods (ZnO NRs) array have been grown by wet chemical method on seeded substrates at low temperature. Gold nanosheet has been deposited by DC magnetron sputtering on the surrounding of the ZnO NRs array at glancing angle, thus creating a three-dimensionally (3D) plasmonic hetero-nanostructure (HNS). The localized surface plasmon resonance (LSPR) is tuned and blue-shifted as the thickness of the gold nanosheet increased. The efficient surface plasmon (SP) excitation, and charge transfer plasmon through tunneling transport and junction conductance elevates the locally electromagnetic field and subsequently enhances surface Raman scattering in ZnO NRs-Au array HNS. An enhanced factor (EF) of 500 can be obtained for the surface enhancement Raman scattering (SERS) response for ZnO NRs-Au array HNS. Photoluminescence spectrum shows Au- mediated blue emission enhancement. The ZnO NRs–Au HNSs show high nonlinear refractive index and nonlinear optical absorption coefficient around 10−5 cm2/W and 1 cm/W, respectively. The ZnO NRs-Au array HNS can provide the figures of merit w = 209.83 and t = 0.59 for the optical switching devices. Photosensitivity and photocatalytic activity are elevated in ZnO NRs-Au array HNS. The ZnO NRs-Au array HNS shows maximal photocurrent enhancement of 69.38% in comparison to the bare ZnO NRs array.
A logical NAND and NOR gate was simulated using bistability behavior in nonlinear medium of Fabry... more A logical NAND and NOR gate was simulated using bistability behavior in nonlinear medium of Fabry-Perot cavity based on the inverse trend of output intensity vs. input intensity. The gate was optimised relative to different cavity parameters, sharp edges between the ON and OFF modes and threshold switching intensity. The real and imaginary parts of the refractive index of the nonlinear medium were utilised to compute numerical results. Finally, gate speed was calculated to be 9.2 Gb/s.
Photoactivity and Light Harvesting in ZnO Nanorods Array / Au/ CuS Heterostructure
Surface Innovations
Zinc oxide (ZnO) nanorod arrays (NRs)/gold (Au)/copper sulfide (CuS) heterostructures were grown ... more Zinc oxide (ZnO) nanorod arrays (NRs)/gold (Au)/copper sulfide (CuS) heterostructures were grown by way of a low-temperature chemical approach, magnetron sputtering deposition and the successive ionic layer absorption and reaction route. The structural characteristics, morphological characteristics, elemental composition, current–voltage characteristics, ultraviolet–visible–near-infrared absorption and photocatalytic and photoelectrochemical properties of the ternary zinc oxide NR/gold/copper sulfide heterostructures were studied. The photocatalytic efficiency of the zinc oxide NRs/gold/copper sulfide heterostructures was higher than that of their zinc oxide NRs/copper sulfide counterparts. The zinc oxide NRs/gold/copper sulfide heterostructures were visible-light-photosensitive due to the lower bandgap of copper sulfide and localized surface plasmon resonance excitation of gold. The Schottky junction can motivate the photogenerated electron–hole to separate and transfer in opposite...
Rectifying Behaviour and Photocatalytic Activity in ZnO Nanorods Array/Ag/CuSe Heterostructure
Journal of Cluster Science
Ag incorporated vertically aligned ZnO nanorods array/CuSe thin film (ZnO NRs/CuSe TF) have been ... more Ag incorporated vertically aligned ZnO nanorods array/CuSe thin film (ZnO NRs/CuSe TF) have been fabricated via a solution route, thermal evaporation and magnetron sputtering process. Ternary ZnO nanorods/Ag/CuSe heterostructure was studied by X-ray diffractometry, field emission-scanning electron microscopy/energy dispersive X ray spectroscopy, current–voltage measurement and a UV–Vis–near IR spectrophotometer. The photocatalytic performance was estimated by the degradation of Rhodamine B solution under UV–Vis light irradiation. The photocatalytic efficiency of the ZnO NRs/Ag/CuSe heterostructure is higher than that of ZnO NRs/Ag and ZnO NRs/CuSe counterparts due to the robust effects of the three functional components coupling. The localized surface plasmon resonance and two Schottky junctions (e.g. Ag/ZnO and Ag/CuSe) motivates photogenerated electron–hole separation and transfer. This work presents an artificial manipulated system to enhance light harvesting, efficient charge separation and transfer, and low recombination rate in solar energy conversion.
Hetero plasmonic 2D and 3D ZnO/Ag nanostructures: electrical and photocatalytic applications
Journal of Materials Science: Materials in Electronics
ZnO thin films (TFs) and nanorods (NRs) array have been synthesized by RF magnetron sputtering an... more ZnO thin films (TFs) and nanorods (NRs) array have been synthesized by RF magnetron sputtering and low temperature wet chemical method, respectively. It is followed by deposition of Ag nanosheet using DC magnetron sputtering, which forms 2D and 3D ZnO/Ag heterointerfaces. This work devotes the significant of thickness, annealing and shape of ZnO–Ag heterojunction on its characteristics. A successful fabrication of ZnO–Ag heterostructure was presented to improve (modify) the conductivity and optical absorption. UV–Vis near IR absorption spectroscopy revealed higher absorption efficiency in the visible region for Ag–ZnO thin film rather than in pure ZnO. The optical response of ZnO–Ag composite based on Gans theory indicates surface plasmon resonance behavior as well in nonspheriod (oblate) Ag nanoislands. The transport behavior of FTO/Ag/ZnO NRs/Cu heterojunction could be useful in variable resistor (varistor). Current voltage characteristic of Ag/ZnO NRs/FTO shows good Schottky behavior. The predicted Schottky barrier height of 1 V was obtained which is not far from the theoretical Schottky–Mott value of 0.8 V. Photocatalytic degradation of Rhodamine B (RhB) was used to evaluate the activity of ZnO NRs/Ag heterostructure. ZnO NRs/Ag heterostructure depicts the best photocatalytic activity due to electronic and plasmonic coupling.
Heteroepitaxial ZnO/CuO thin film and nanorods array: photoconductivity and field emission effect
Journal of Materials Science: Materials in Electronics
ZnO thin film and nanorods array have been synthesized by RF magnetron sputtering and low tempera... more ZnO thin film and nanorods array have been synthesized by RF magnetron sputtering and low temperature wet chemical method, respectively. It is followed by deposition of Cu nanosheet using DC magnetron sputtering, which was oxidized subsequently to form 2D and 3D ZnO/CuO heterointerfaces. A successful fabrication of heteroepitaxial ZnO–CuO thin film was presented to improve the interface quality, crystallinity and conformal characteristic of CuO sheet. ZnO/CuO thin film revealed higher absorption efficiency in the visible region in comparison to pure ZnO. The rectifying behavior of n-ZnO/p-CuO junction could be useful in photoactive and photoconductive devices, while the uni-polar transport of p-CuO/n-ZnO thin film is beneficial for optical switching. This photoactivity attributed to extended light absorption and effective transfer of photogenerated carriers. The as-synthesized ZnO–Cu composite was determined to be a hierarchical heterostructure consisting of ZnO nanorods and Cu nanosheets with intimate hetero-interfaces. The formation of n+-Cu/n-ZnO heterointerface cause to electrostatic field which facilitates electron emission.
The role of nitrogen pressure on characteristics of reactively sputter deposited (Ti,Cu)N nanocrystalline thin films
(Ti,Cu)N thin films were deposited on Si (111), glass slide, quartz substrates using reactive DC ... more (Ti,Cu)N thin films were deposited on Si (111), glass slide, quartz substrates using reactive DC magnetron sputtering in molecular nitrogen ambient. The effect of different nitrogen pressure on the characteristic of (Ti,Cu)N films was examined. Structural analysis of the films was identified by X- ray diffraction (XRD) technique. As nitrogen pressure increased, film structure changes from random oriented growth to preferred ones. Lattice constant expansion shows that Ti soluted in Cu3N structure. Surface morphology and chemical composition of the films were studied by scanning electron microscope/ energy dispersive X- ray spectroscopy (SEM/EDX). At higher nitrogen pressure, films have clear nano-metric grain boundaries. The films were aggregated as spherical grains. Atomic titanium to copper (Ti:Cu) ratio of (Ti,Cu)N films was less than that of original target. Optical study was performed by Vis- near IR transmittance spectroscopy. Film thickness and absorption coefficient were extr...
Effect of nitrogen partial pressure on reactive magnetron sputtering from Ti13Cu87 metalloid target: simulation of chemical composition
Ukrainian Journal of Physics
Ti13Cu87 sintered composite target was reactively sputtered at Ar- N2 gas mixtures, and sputtered... more Ti13Cu87 sintered composite target was reactively sputtered at Ar- N2 gas mixtures, and sputtered species were deposited on Si (111) substrates. In this study, the pressure-dependent target mode variation of a Ti13Cu87–N2 system was investigated by measuring the N2 partial pressure, deposition rate, target voltage, and Ti and Cu concentration for various reactive N2 gas flow ratios. The Ti13Cu87 target surface begins to be nitrided with increasing N2 flow ratio. It is considered caused by the absorption and implantation of N2 gas on the Ti13Cu87 target surface. Hence, deposition rate was reduced due to lower sputtering yield and more scattering for mass transport between target- substrate spacing. Secondary electron emission yield from nitrided target surface is further than that of unnitrided target surface. Therefore, at constant sputtering power, target voltage decreased as the N2 partial pressure increased. By means of TRIM.SP Monte-Carlo simulation, the particle reflection coef...
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