Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer...Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.展开更多
In this paper, the membrane capacitance (Cm), which was obtained from the electro- chemical impedance spectroscopy (EIS) method, was used to characterize the effect of pH value on the self-assembled monolayers (SAMs) ...In this paper, the membrane capacitance (Cm), which was obtained from the electro- chemical impedance spectroscopy (EIS) method, was used to characterize the effect of pH value on the self-assembled monolayers (SAMs) of octadecanethiol(18SH) for the first time. The results not only strongly proved that inorganic ions could penetrate the SAMs of 18SH, but also ascertained that SAMs of 18SH were not an absolute of free of ion-penetration. Verifying the existence of pin-holes in the octadecanethiol SAMs was the main contribution of this paper, which coincided with the former conjecture very well.展开更多
A two-dimensional electrical SiC MOS interface model including interface and near-interface traps is established based on the relevant tunneling and interface Shockley–Read–Hall model. The consistency between simula...A two-dimensional electrical SiC MOS interface model including interface and near-interface traps is established based on the relevant tunneling and interface Shockley–Read–Hall model. The consistency between simulation results and measured data in the different temperatures shows that this interface model can accurately describe the capture and emission performance for near-interface oxide traps, and can well explain the hysteresis-voltage response with increasing temperature, which is intensified by the interaction between deep oxide traps and shallow oxide traps. This also indicates that the near-interface traps result in an increase of threshold-voltage shift in SiC MOSFET with increasing temperature.展开更多
1 Introduction In recent years porous carbons have been widely used in many fields such as energy storage(Mc Creery,2008;Liu et al,2009;Ho et al,2014;Yang et al,2015),adsorption,wastewater treatment,air purification
The purpose of this paper is to show the influence of the edge-effect on the electric field distribution, and hence on the inner capacitance and outer capacitance of a cylindrical capacitor surrounded by an insulating...The purpose of this paper is to show the influence of the edge-effect on the electric field distribution, and hence on the inner capacitance and outer capacitance of a cylindrical capacitor surrounded by an insulating medium. To generalize the results, a two-dimensional axisymmetric finite element model of a cylindrical capacitor has been generated and the problem has been resolved taking into account the distance between the conductors for a complete set of dimensions. The available obtained results have been compared with previous published works. Finally, using statistical tools, the mathematical expression for computing the relationship between capacitance and insulation gap and cylindrical plates dimensions has been obtained.展开更多
Models of threshold voltage and subthreshold swing, including the fringing-capacitance effects between the gate electrode and the surface of the source/drain region, are proposed. The validity of the proposed models i...Models of threshold voltage and subthreshold swing, including the fringing-capacitance effects between the gate electrode and the surface of the source/drain region, are proposed. The validity of the proposed models is confirmed by the good agreement between the simulated results and the experimental data. Based on the models, some factors impacting the threshold voltage and subthreshold swing of a GeOI metal-oxide-semiconductor field-effect transistor（MOSFET） are discussed in detail and it is found that there is an optimum thickness of gate oxide for definite dielectric constant of gate oxide to obtain the minimum subthreshold swing. As a result, it is shown that the fringing-capacitance effect of a shortchannel GeOI MOSFET cannot be ignored in calculating the threshold voltage and subthreshold swing.展开更多
The magneto-electric coupling and magneto-capacitance effect of a layer composite ferromagnet/ piezoelectric/ferromagnet was investigated. Several resonant peaks were observed on the curves of the capacitance versus f...The magneto-electric coupling and magneto-capacitance effect of a layer composite ferromagnet/ piezoelectric/ferromagnet was investigated. Several resonant peaks were observed on the curves of the capacitance versus frequency. The resonant peaks were found to shift under an applied magnetic field, and the impedance of the sample can be changed from capacitive to inductive ones with changing the field. Thus, giant negative and positive magneto-capacitance effects can be observed simultaneously under a magnetic field less than 1 k Oe near the resonant points. Experimental and theoretical analysis showed that such magnetically tuned variation in impedance originates from the magnetic field-induced change of the compliances of the magnetic phase of the composite.展开更多
Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the e...Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.展开更多
We performed an experimental investigation on the electromagnetic effect and the plasma radial uniformity in a larger-area, cylindrical capacitively coupled plasma reactor. By utilizing a floating hairpin probe, depen...We performed an experimental investigation on the electromagnetic effect and the plasma radial uniformity in a larger-area, cylindrical capacitively coupled plasma reactor. By utilizing a floating hairpin probe, dependences of the plasma radial density on the driving frequency and the radio-frequency power over a wide pressure range of 5-40 Pa were presented. At a relatively low frequency(LF, e.g. 27 MHz), an evident peak generally appears near the electrode edge for all pressures investigated here due to the edge field effect, while at a very high frequency(VHF, e.g.60 or 100 MHz), the plasma density shows a sharp peak at the discharge center at lower pressures, indicating a strong standing wave effect. As the RF power increases, the center-peak structure of plasma density becomes more evident. With increasing the pressure, the standing wave effect is gradually overwhelmed by the ‘stop band’ effect, resulting in a transition in the plasma density profile from a central peak to an edge peak. To improve the plasma radial uniformity, a LF source is introduced into the VHF plasma by balancing the standing wave effect with the edge effect. A much better plasma uniformity can be obtained if one chooses appropriate LF powers, pressures and other corresponding discharge parameters.展开更多
A two-dimensional （2D） fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma （CCP） reactor. The plasma–wall interaction ...A two-dimensional （2D） fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma （CCP） reactor. The plasma–wall interaction （including the deposition） is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N2 /NH3 ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing the electron density significantly.展开更多
An electrical characteristic model of organic thin film transistors(OTFTs)is presented.The model is based on the capacitance modulation principle,i.e.the accumulated charges in the conductive channel are induced by th...An electrical characteristic model of organic thin film transistors(OTFTs)is presented.The model is based on the capacitance modulation principle,i.e.the accumulated charges in the conductive channel are induced by the gate capacitance under an electric field.The current-voltage characteristics of the presented model are compared with the experimental data.According to the electrical characteristics of the model,it is explained that the operating process of OTFTs is actually modulated by the capacitance.The gate capacitance,the contact resistance,the contact barrier,and the field-effect mobility have a significant effect on the performance of OTFTs.展开更多
For years, capacitive effects have been the subject of research [1] and [2]. The capacitive effects are discrete capacitors that appear between active conductors of power lines and between them with the ground plane, ...For years, capacitive effects have been the subject of research [1] and [2]. The capacitive effects are discrete capacitors that appear between active conductors of power lines and between them with the ground plane, generating capacitive reactive power to the network [1] and [2]. Indeed, it must be noted that these effects affect the windings of the transformer when the coupling is in star or triangle. This study is conducted to show that capacitive effects affect transformer windings differently when coupling is in stars or triangles. The results obtained are interesting and can be exploited in electrical transmission networks to ensure a long lifespan of transformers.展开更多
The characteristic behavior of the inductance and capacitance of multi junction ac Josephson effect in superconductor has been presented. Few parameters characterizing the behavior of Josephson junctions are needed to...The characteristic behavior of the inductance and capacitance of multi junction ac Josephson effect in superconductor has been presented. Few parameters characterizing the behavior of Josephson junctions are needed to evaluate for technological applications. In this paper, the inductance and capacitance of the multi Josephson junction connected in parallel are evaluated, using simple classical argument. The numerical results for inductance and capacitance have also been included, indicating few technological applications.展开更多
Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27....Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.展开更多
Radio frequency capacitively coupled plasmas(RF CCPs)play a pivotal role in various applications in etching and deposition processes on a microscopic scale in semiconductor manufacturing.In the discharge process,the p...Radio frequency capacitively coupled plasmas(RF CCPs)play a pivotal role in various applications in etching and deposition processes on a microscopic scale in semiconductor manufacturing.In the discharge process,the plasma series resonance(PSR)effect is easily observed in electrically asymmetric and geometrically asymmetric discharges,which could largely influence the power absorption,ionization rate,etc.In this work,the PSR effect arising from geometrically and electrically asymmetric discharge in argon-oxygen mixture gas is mainly investigated by using a plasma equivalent circuit model coupled with a global model.At relatively low pressures,as Ar content(α)increases,the inductance of the bulk is weakened,which leads to a more obvious PSR phenomenon and a higher resonance frequency(ω_(psr)).When the Ar content is fixed,varying the pressure and gap distance could also have different effects on the PSR effect.With the increase of the pressure,the PSR frequency shifts towards the higher order,but in the case of much higher pressure,the PSR oscillation would be strongly damped by frequent electron-neutral collisions.With the increase of the gap distance,the PSR frequency becomes lower.In addition,electrically asymmetric waveforms applied to a geometrically asymmetric chamber may weaken or enhance the asymmetry of the discharge and regulate the PSR effect.In this work,the Ar/O_(2) electronegative mixture gas is introduced in a capacitive discharge to study the PSR effect under geometric asymmetry effect and electrical asymmetry effect,which can provide necessary guidance in laboratory research and current applications.展开更多
Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates ...Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates so that the capacitor fringe effect cannot be neglected in the design. Electricmagnetic Finite Element Method （FEM） software ANSOFF-Maxwell is employed to analyze the fringe effect of a grid strip capacitor. The analysis includes capacitance changes with change of overlap length, overlap width, plate thickness, grid strip density etc. The results show that fringe effect leads to non-linear change of grid strip capacitance with the change of overlap length and width, that the capacitance increases with the increase of grid strip width and plate thickness, and that sensitivity can be improved through the increase of grid strip density in the condition of identical total overlap area, but linearity is reduced.展开更多
The conformal mapping of an electric field has been employed to develop an accurate parasitic capacitance model for nanoscale fin field-effect transistor（Fin FET） device. Firstly, the structure of the dual-layer spa...The conformal mapping of an electric field has been employed to develop an accurate parasitic capacitance model for nanoscale fin field-effect transistor（Fin FET） device. Firstly, the structure of the dual-layer spacers and the gate parasitic capacitors are thoroughly analyzed. Then, the Cartesian coordinate is transferred into the elliptic coordinate and the equivalent fringe capacitance model can be built-up by some arithmetical operations. In order to validate our proposed model, the comparison of statistical analysis between the proposed calculation and the 3D-TCAD simulation has been carried out, and several different material combinations of the dual-k structure have been considered. The results show that the proposed analytical model can accurately calculate the fringe capacitance of the Fin FET device with dual-k spacers.展开更多
Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it...Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it continues to encounter challenges including rapid capacity degradation,structural instability,and Jahn-Teller effect.Herein,a crystal and electron synergistically regulation engineering strategy is proposed for the suppression of the Jahn-Teller effect and the improvement of ammonium ion storage dynamics in F doped MnO_(2)(MnOF).The induced action of F ions transforms the MnO_(2)structure from the original cubic[MnO_(6)]octahedron into an asymmetric[Mn(OF)_(6)]octahedron with electron redistribution,and generates a localized charge imbalance along the O-Mn-F pathway,which promotes electron transfer from Mn to F direction,accelerates electron transfer,and reduces the energy barrier of ammonium ion diffusion.As a result,the prepared MnOF exhibited a maximum salt adsorption capacity of 144.3 mg g^(−1)and an exceptionally high salt adsorption rate of 18.25 mg g^(−1)min^(-1),along with outstanding cycling stability.Besides,ex/in situ characterizations reveal that in MnOF,the formation/breaking of hydrogen bond is accompanied by the insertion/deinsertion of NH_(4)^(+).Therefore,the rational introduction of highly electronegative anions provides a new direction for the development of advanced CDI electrode materials.展开更多
The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC, continuous expressions of surface potential and ...The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC, continuous expressions of surface potential and inversion layer carrier density are derived. Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.展开更多
基金supported by the Shenzhen Science and Technology Program(JCYJ20230808105111022,JCYJ20220818095806013)Natural Science Foundation of Guangdong(2023A1515012267)+1 种基金the National Natural Science Foundation of China(22178223)the Royal Society/NSFC cost share program(IEC\NSFC\223372).
文摘Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.
基金This work was supported by the NNSFC (29973026).
文摘In this paper, the membrane capacitance (Cm), which was obtained from the electro- chemical impedance spectroscopy (EIS) method, was used to characterize the effect of pH value on the self-assembled monolayers (SAMs) of octadecanethiol(18SH) for the first time. The results not only strongly proved that inorganic ions could penetrate the SAMs of 18SH, but also ascertained that SAMs of 18SH were not an absolute of free of ion-penetration. Verifying the existence of pin-holes in the octadecanethiol SAMs was the main contribution of this paper, which coincided with the former conjecture very well.
基金Supported by the Science Challenge Project under Grant No TZ2018003
文摘A two-dimensional electrical SiC MOS interface model including interface and near-interface traps is established based on the relevant tunneling and interface Shockley–Read–Hall model. The consistency between simulation results and measured data in the different temperatures shows that this interface model can accurately describe the capture and emission performance for near-interface oxide traps, and can well explain the hysteresis-voltage response with increasing temperature, which is intensified by the interaction between deep oxide traps and shallow oxide traps. This also indicates that the near-interface traps result in an increase of threshold-voltage shift in SiC MOSFET with increasing temperature.
基金financial support from the National Natural Science Foundation of China (51274015)National Program on Key Basic Research Project (973 Program) (2014CB846000)Test Fund of Peking University
文摘1 Introduction In recent years porous carbons have been widely used in many fields such as energy storage(Mc Creery,2008;Liu et al,2009;Ho et al,2014;Yang et al,2015),adsorption,wastewater treatment,air purification
文摘The purpose of this paper is to show the influence of the edge-effect on the electric field distribution, and hence on the inner capacitance and outer capacitance of a cylindrical capacitor surrounded by an insulating medium. To generalize the results, a two-dimensional axisymmetric finite element model of a cylindrical capacitor has been generated and the problem has been resolved taking into account the distance between the conductors for a complete set of dimensions. The available obtained results have been compared with previous published works. Finally, using statistical tools, the mathematical expression for computing the relationship between capacitance and insulation gap and cylindrical plates dimensions has been obtained.
基金supported by the National Natural Science Foundation of China(Grant No.61274112)
文摘Models of threshold voltage and subthreshold swing, including the fringing-capacitance effects between the gate electrode and the surface of the source/drain region, are proposed. The validity of the proposed models is confirmed by the good agreement between the simulated results and the experimental data. Based on the models, some factors impacting the threshold voltage and subthreshold swing of a GeOI metal-oxide-semiconductor field-effect transistor（MOSFET） are discussed in detail and it is found that there is an optimum thickness of gate oxide for definite dielectric constant of gate oxide to obtain the minimum subthreshold swing. As a result, it is shown that the fringing-capacitance effect of a shortchannel GeOI MOSFET cannot be ignored in calculating the threshold voltage and subthreshold swing.
文摘The magneto-electric coupling and magneto-capacitance effect of a layer composite ferromagnet/ piezoelectric/ferromagnet was investigated. Several resonant peaks were observed on the curves of the capacitance versus frequency. The resonant peaks were found to shift under an applied magnetic field, and the impedance of the sample can be changed from capacitive to inductive ones with changing the field. Thus, giant negative and positive magneto-capacitance effects can be observed simultaneously under a magnetic field less than 1 k Oe near the resonant points. Experimental and theoretical analysis showed that such magnetically tuned variation in impedance originates from the magnetic field-induced change of the compliances of the magnetic phase of the composite.
基金financial support from National Natural Science Foundation of China(91534123,91834303,U1862117)supported by the State Key Laboratory of Multiphase Complex Systems(MPCS-2017-A-01)support by State key laboratory of Multiphase Complex Systems(MPCS)Facility Upgradation Program
文摘Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.
基金funded by National Natural Science Foundation of China (Nos. 11875100, 11935005 and 11722541)financial support from the China Scholarship Council。
文摘We performed an experimental investigation on the electromagnetic effect and the plasma radial uniformity in a larger-area, cylindrical capacitively coupled plasma reactor. By utilizing a floating hairpin probe, dependences of the plasma radial density on the driving frequency and the radio-frequency power over a wide pressure range of 5-40 Pa were presented. At a relatively low frequency(LF, e.g. 27 MHz), an evident peak generally appears near the electrode edge for all pressures investigated here due to the edge field effect, while at a very high frequency(VHF, e.g.60 or 100 MHz), the plasma density shows a sharp peak at the discharge center at lower pressures, indicating a strong standing wave effect. As the RF power increases, the center-peak structure of plasma density becomes more evident. With increasing the pressure, the standing wave effect is gradually overwhelmed by the ‘stop band’ effect, resulting in a transition in the plasma density profile from a central peak to an edge peak. To improve the plasma radial uniformity, a LF source is introduced into the VHF plasma by balancing the standing wave effect with the edge effect. A much better plasma uniformity can be obtained if one chooses appropriate LF powers, pressures and other corresponding discharge parameters.
基金Project supported by the China Postdoctoral Science Foundation (Grant No. 2012M511603)the National Natural Science Foundation of China (Grant Nos. 11105057 and 10775025)+1 种基金the Natural Science Foundation of Hubei Province of China (Grant No. 2007ABA035)the Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0073)
文摘A two-dimensional （2D） fluid model is presented to study the behavior of silicon plasma mixed with SiH4 , N2 , and NH3 in a radio-frequency capacitively coupled plasma （CCP） reactor. The plasma–wall interaction （including the deposition） is modeled by using surface reaction coefficients. In the present paper we try to identify, by numerical simulations, the effect of variations of the process parameters on the plasma properties. It is found from our simulations that by increasing the gas pressure and the discharge gap, the electron density profile shape changes continuously from an edge-high to a center-high, thus the thin films become more uniform. Moreover, as the N2 /NH3 ratio increases from 6/13 to 10/9, the hydrogen content can be significantly decreased, without decreasing the electron density significantly.
基金Supported by the National Natural Science Foundation of China under Grant No 51272022the National Basic Research Program of China under Grant No 2010CB327704+2 种基金New Century Excellent Thlents in University under Grant No NCET-10-0220the Research Fund for the Doctoral Program of Higher Education under Grant No 20120009130005the Fundamental Research Funds for the Central Universities under Grant No 2012JBZ001.
文摘An electrical characteristic model of organic thin film transistors(OTFTs)is presented.The model is based on the capacitance modulation principle,i.e.the accumulated charges in the conductive channel are induced by the gate capacitance under an electric field.The current-voltage characteristics of the presented model are compared with the experimental data.According to the electrical characteristics of the model,it is explained that the operating process of OTFTs is actually modulated by the capacitance.The gate capacitance,the contact resistance,the contact barrier,and the field-effect mobility have a significant effect on the performance of OTFTs.
文摘For years, capacitive effects have been the subject of research [1] and [2]. The capacitive effects are discrete capacitors that appear between active conductors of power lines and between them with the ground plane, generating capacitive reactive power to the network [1] and [2]. Indeed, it must be noted that these effects affect the windings of the transformer when the coupling is in star or triangle. This study is conducted to show that capacitive effects affect transformer windings differently when coupling is in stars or triangles. The results obtained are interesting and can be exploited in electrical transmission networks to ensure a long lifespan of transformers.
文摘The characteristic behavior of the inductance and capacitance of multi junction ac Josephson effect in superconductor has been presented. Few parameters characterizing the behavior of Josephson junctions are needed to evaluate for technological applications. In this paper, the inductance and capacitance of the multi Josephson junction connected in parallel are evaluated, using simple classical argument. The numerical results for inductance and capacitance have also been included, indicating few technological applications.
基金Projects(30571779,10775085) supported by the National Natural Science Foundation of ChinaProject(Z07000200540704) supported by Beijing Municipal Science and Technology Commission,China
文摘Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12020101005 and 11975067)。
文摘Radio frequency capacitively coupled plasmas(RF CCPs)play a pivotal role in various applications in etching and deposition processes on a microscopic scale in semiconductor manufacturing.In the discharge process,the plasma series resonance(PSR)effect is easily observed in electrically asymmetric and geometrically asymmetric discharges,which could largely influence the power absorption,ionization rate,etc.In this work,the PSR effect arising from geometrically and electrically asymmetric discharge in argon-oxygen mixture gas is mainly investigated by using a plasma equivalent circuit model coupled with a global model.At relatively low pressures,as Ar content(α)increases,the inductance of the bulk is weakened,which leads to a more obvious PSR phenomenon and a higher resonance frequency(ω_(psr)).When the Ar content is fixed,varying the pressure and gap distance could also have different effects on the PSR effect.With the increase of the pressure,the PSR frequency shifts towards the higher order,but in the case of much higher pressure,the PSR oscillation would be strongly damped by frequent electron-neutral collisions.With the increase of the gap distance,the PSR frequency becomes lower.In addition,electrically asymmetric waveforms applied to a geometrically asymmetric chamber may weaken or enhance the asymmetry of the discharge and regulate the PSR effect.In this work,the Ar/O_(2) electronegative mixture gas is introduced in a capacitive discharge to study the PSR effect under geometric asymmetry effect and electrical asymmetry effect,which can provide necessary guidance in laboratory research and current applications.
基金Supported by the National Natural Science Foundation of China （ No. 60903195 ） and the Key Technological Problems Tackling Project of Wuhan （No. 200750499172）.
文摘Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates so that the capacitor fringe effect cannot be neglected in the design. Electricmagnetic Finite Element Method （FEM） software ANSOFF-Maxwell is employed to analyze the fringe effect of a grid strip capacitor. The analysis includes capacitance changes with change of overlap length, overlap width, plate thickness, grid strip density etc. The results show that fringe effect leads to non-linear change of grid strip capacitance with the change of overlap length and width, that the capacitance increases with the increase of grid strip width and plate thickness, and that sensitivity can be improved through the increase of grid strip density in the condition of identical total overlap area, but linearity is reduced.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574056 and 61204038)the Natural Science Foundation of Shanghai,China(Grant No.14ZR1412000)
文摘The conformal mapping of an electric field has been employed to develop an accurate parasitic capacitance model for nanoscale fin field-effect transistor（Fin FET） device. Firstly, the structure of the dual-layer spacers and the gate parasitic capacitors are thoroughly analyzed. Then, the Cartesian coordinate is transferred into the elliptic coordinate and the equivalent fringe capacitance model can be built-up by some arithmetical operations. In order to validate our proposed model, the comparison of statistical analysis between the proposed calculation and the 3D-TCAD simulation has been carried out, and several different material combinations of the dual-k structure have been considered. The results show that the proposed analytical model can accurately calculate the fringe capacitance of the Fin FET device with dual-k spacers.
基金financial support from the National Natural Science Foundation of China(22108032 and 22178055)the Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents+1 种基金the support of characterization from the Dongguan University of Technology Analytical and Testing Centerthe Guangdong Provincial Key Laboratory of Intelligent Disaster Prevention and Emergency Technologies for Urban Lifeline Engineering(2022)(Grant No.2022B1212010016).
文摘Layered manganese dioxide(δ-MnO_(2))is considered a promising ammonium ion capture electrode material for capacitive deionization(CDI)attributed to its high theoretical capacity and cost-effectiveness.Nevertheless,it continues to encounter challenges including rapid capacity degradation,structural instability,and Jahn-Teller effect.Herein,a crystal and electron synergistically regulation engineering strategy is proposed for the suppression of the Jahn-Teller effect and the improvement of ammonium ion storage dynamics in F doped MnO_(2)(MnOF).The induced action of F ions transforms the MnO_(2)structure from the original cubic[MnO_(6)]octahedron into an asymmetric[Mn(OF)_(6)]octahedron with electron redistribution,and generates a localized charge imbalance along the O-Mn-F pathway,which promotes electron transfer from Mn to F direction,accelerates electron transfer,and reduces the energy barrier of ammonium ion diffusion.As a result,the prepared MnOF exhibited a maximum salt adsorption capacity of 144.3 mg g^(−1)and an exceptionally high salt adsorption rate of 18.25 mg g^(−1)min^(-1),along with outstanding cycling stability.Besides,ex/in situ characterizations reveal that in MnOF,the formation/breaking of hydrogen bond is accompanied by the insertion/deinsertion of NH_(4)^(+).Therefore,the rational introduction of highly electronegative anions provides a new direction for the development of advanced CDI electrode materials.
文摘The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC, continuous expressions of surface potential and inversion layer carrier density are derived. Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.
