Artificial synapses utilizing spike signals are essential elements of new generation brain-inspired computers.In this paper,we realize light-stimulated adaptive artificial synapse based on nanocrystalline zinc oxide f...Artificial synapses utilizing spike signals are essential elements of new generation brain-inspired computers.In this paper,we realize light-stimulated adaptive artificial synapse based on nanocrystalline zinc oxide film.The artificial synapse photoconductivity shows spike-type signal response,long and short-term memory(LTM and STM),STM-to-LTM transition and paired-pulse facilitation.It is also retaining the memory of previous exposures and demonstrates spike-frequency adaptation properties.A way to implement neurons with synaptic depression,tonic excitation,and delayed accelerating types of response under the influence of repetitive light signals is discussed.The developed artificial synapse is able to become a key element of neuromorphic chips and neuromorphic sensorics systems.展开更多
A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge...A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge balance and suppresses the substrate-assisted depletion effect. Secondly, the new electric field peak produced by the P/P junction modulates the surface electric field distribution. Both of these result in a high breakdown voltage (BV). In addition, due to the same conduction paths, the specific on-resistance (Ron,sp) of the PD SJ-LDMOS is approximately identical to the conventional SJ-LDMOS. Simulation results indicate that the average value of the surface lateral electric field of the PD SJ-LDMOS reaches 20 V/μm at a 15 μm drift length, resulting in a BV of 300 V.展开更多
Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor (MOS) structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are ch...Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor (MOS) structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are characterized by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, capacitance-voltage (C-V) and current-voltage characteristics. It is demonstrated that wet thermal annealing at relatively higher temperature such as 550 ℃ can lead to Ge incorporation in HfO2 and the partial crystallization of HfO2, which should be responsible for the serious degradation of the electrical characteristics of the TaN/HfO2/Ge MOS capacitors. However, wet thermal annealing at 400 ℃ can decrease the GeOx interlayer thickness at the HfO2/Ge interface, resulting in a significant reduction of the interface states and a smaller effective oxide thickness, along with the introduction of a positive charge in the dielectrics due to the hydrolyzable property of GeOx in the wet ambient. The pre-growth of a thin GeO2 passivation layer can effectively suppress the interface states and improve the C V characteristics for the as-prepared HfO2 gated Ge MOS capacitors, but it also dissembles the benefits of wet thermal annealing to a certain extent.展开更多
This paper presents a numerical study on the simultaneous reconstruction of temperature and volume fraction fields of soot and metal-oxide nanoparticles in an axisymmetric nanofluid fuel sooting flame based on the rad...This paper presents a numerical study on the simultaneous reconstruction of temperature and volume fraction fields of soot and metal-oxide nanoparticles in an axisymmetric nanofluid fuel sooting flame based on the radiative energy images captured by a charge-coupled device(CCD)camera.The least squares QR decomposition method was introduced to deal with the reconstruction inverse problem.The effects of ray numbers and measurement errors on the reconstruction accuracy were investigated.It was found that the reconstruction accuracies for volume fraction fields of soot and metaloxide nanoparticles were easily affected by the measurement errors for radiation intensity,whereas only the metal-oxide volume fraction field reconstruction was more sensitive to the measurement error for the volume fraction ratio of metaloxide nanoparticles to soot.The results show that the temperature,soot volume fraction,and metal-oxide nanoparticles volume fraction fields can be simultaneously and accurately retrieved for exact and noisy data using a single CCD camera.展开更多
Nanoclusters(NCs)have been demonstrated of outstanding performance in electrochemical energy storage and conversion technologies due to their strong quantum confinement effects and strong interaction with supports.Her...Nanoclusters(NCs)have been demonstrated of outstanding performance in electrochemical energy storage and conversion technologies due to their strong quantum confinement effects and strong interaction with supports.Here,we developed a class of ultrafine metal-oxide(MOx,M=Fe,Co and Ni)NCs incorporated with iron phthalocyanine(FePc),MOx/FePc-G,supported on graphene as high-performance catalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and carbon dioxide reduction(CO2RR).The high activities for ORR and OER are attributed to the electron donation and accepting ability of the highly redox active of FePc-G that could tune the properties of MOx.The FeOx/FePc-G exhibits an extremely positive half-wave potential(E1/2)of 0.888 and 0.610 V for ORR in alkaline and neutral conditions,respectively,which is around 60 mV more positive than that of Pt/C.And NiOx/FePc-G shows similar OER activity with the state-of-the-art catalysts,Ir/C,and better performance than NiFeO NCs supported on graphene.Remarkably,the CoOx/FePc-G and NiOx/FePc-G show high activity and selectivity to reduce CO2 into CO with a low onset potential of-0.22 V(overpotential is 0.11 V).展开更多
Elecrochemical CO_(2) reduction is a promising route to convert CO_(2) into the value added chemicals,and to control the increasing accumulation of 002 in the atmosphere.The CO_(2) molecule is stable and chemically in...Elecrochemical CO_(2) reduction is a promising route to convert CO_(2) into the value added chemicals,and to control the increasing accumulation of 002 in the atmosphere.The CO_(2) molecule is stable and chemically inert,so a highly efficient electrocatalyst is required for CO_(2) reduction.The single atoms with metal oxdde support is a new fronder in CO_(2) reduction.The supported single atoms contain disperse isolated atoms with an appropriate support maxcimize the atom efficiency of metals for boosting the catalytc perfomance.In this review,we had discussed state-of-the-art research on the synthestis of single atoms supported on the metal oxdde for boosting catalytic activity for CO_(2) reduction and special emphasis is placed on the influence of single atoms supported on metal oxdde on the CO_(2) reduction.Futhermore,we had discussed the challenges,and opportunities for paving the development of single atoms with metal support and their application in ecrocatalytic CO_(2) reduction.展开更多
The ammonia decomposition for the production of carbon-free hydrogen has triggered great attention yet still remains challenging due to its sluggish kinetics,posting the importance of precise design of efficient catal...The ammonia decomposition for the production of carbon-free hydrogen has triggered great attention yet still remains challenging due to its sluggish kinetics,posting the importance of precise design of efficient catalysts for ammonia decomposition under low temperatures.Constructing the metal-support interaction and interface is one of the most important strategies for promoting catalysts.In this work,by coating ceria onto the Ni nanoparticles(NPs),we discover that the Ni-CeO_(2)interfaces create an exceptional effect to enhance the catalytic decomposition of ammonia by over 10 folds,compared with the pristine Ni.The kinetic analysis demonstrates that the recombinative N2 desorption is the rate-determining step(RDS)and the Ni-CeO_(2)interface greatly increases the RDS.Based on these understandings,a strategy to fabricate the Ni/CeO_(2)catalyst with abundant Ni-Ce-O interfaces via one-pot sol-gel method was employed(hereafter denoted to s-Ni/CeO_(2)).The s-Ni/CeO_(2)catalyst shows a high activity for ammonia decomposition,achieving a H_(2)formation rate of 10.5 mmol gcat1 min^(-1)at 550℃.Combined with a series of characterizations,the relationship between the catalyst structure and the performance was investigated for further understanding the effect of metal-oxide interfaces.展开更多
A series of multiphase metal-oxide catalysts(MnOx/γ-Al_(2)O_(3),CuOx/γ-Al_(2)O_(3),FeO_(x/γ)-Al_(2)O_(3),CeO_(x)/γ-Al_(2)O_(3)and LaOx/γ-Al_(2)O_(3))were prepared for plasma-catalyst degradation of multicomponent...A series of multiphase metal-oxide catalysts(MnOx/γ-Al_(2)O_(3),CuOx/γ-Al_(2)O_(3),FeO_(x/γ)-Al_(2)O_(3),CeO_(x)/γ-Al_(2)O_(3)and LaOx/γ-Al_(2)O_(3))were prepared for plasma-catalyst degradation of multicomponent volatile organic compounds(VOCs,such as toluene,acetone and ethyl acetate).The results reveal that the degradation efficiency(DE)of acetone,toluene and ethyl acetate in the DDBD system can be arranged as follows:Mn_(2)O_(3)/γ-Al_(2)O_(3)>Fe2O3/γ-Al_(2)O_(3)>CuO_(/γ)-Al_(2)O_(3)>CeO_(2)/γ-Al_(2)O_(3)>La_(2)O_(3)/γ-Al_(2)O_(3)>γ-Al_(2)O_(3),and the highest DE(49.5%for acetone,93.3%for toluene and 79.8%for ethyl acetate)is obtained in Mn_(2)O_(3)/γ-Al_(2)O_(3)+double dielectric barrier discharge(DDBD)system at specific input energy(SIE)of 700 J/L.Compared with the other catalysts,Mn_(2)O_(3)/γ-Al_(2)O_(3)also exhibits the most significant inhibitory effect on the production of ozone(O3).On the other hand,CeO_(2)/γ-Al_(2)O_(3)and La_(2)O_(3)/γ-Al_(2)O_(3)catalysts display different catalytic selectivity.Both catalysts can slightly raise the DE of VOCs and remarkably facilitate VOCs’mineralization.The carbon balance(CB)is increased by 30.2%and 38.8%,and the CO_(2)selectivity(SCO_(2))is raised by 70.5%and 11.9%in the CeO_(2)/γ-Al_(2)O_(3)+DDBD system and La_(2)O_(3)/γ-Al_(2)O_(3)+DDBD system at SIE of 700 J/L,respectively.To further understand the catalytic effect of the catalysts,the adsorption of O3on different catalysts was simulated by a DFT model.According to the results of the DFT model,it is found that the adsorption energy of other metal oxides seems to be used as a reference for catalytic effect to a certain extent except CeO_(2).The higher the absolute values of adsorption energy,the higher the improvement of VOCs degradation efficiency by catalyst.展开更多
The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1...The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.展开更多
With the growing applications of nanofluid flame, the monitoring and controlling of its combustion process is of paramount importance. Thus, it is necessary to develop diagnosing methods which can simultaneously image...With the growing applications of nanofluid flame, the monitoring and controlling of its combustion process is of paramount importance. Thus, it is necessary to develop diagnosing methods which can simultaneously image important parameters such as temperature and volume fractions of soot, metal-oxide nanoparticles. Tomographic emission spectroscopy is an effective method which has been proposed for this purpose. However, the inversion process was only reported with least-squares QR decomposition(LSQR) so far and there are numerous well-established reconstruction algorithms which have not been utilized yet.Thus, this work aims to perform systematic comparative studies on several representative algorithms for the inversion process. In the simulative studies, algorithms including Tikhonov regularization, algebraic reconstruction technique(ART), LSQR,Landweber algorithm, maximum likelihood expectation maximization(MLEM), and ordered subset expectation maximization(OSEM) were discussed. The effects of the number of iterations, the signal-to-noise ratio, and the number of projections and the calibration error in projection angles on the performance of the algorithms were investigated. Advice on selecting the suitable algorithms under different application conditions is then provided according to the extensive numerical studies.展开更多
Aligned carbon nanotube films coated with amorphous carbon were developed into novel templates by atomic layer deposition. Freestanding macroscopic metal-oxide nanotube films were then successfully synthesized by usin...Aligned carbon nanotube films coated with amorphous carbon were developed into novel templates by atomic layer deposition. Freestanding macroscopic metal-oxide nanotube films were then successfully synthesized by using these templates. The reactive amorphous carbon layer greatly improved the nuclei density, which ensured the high quality of the films and allowed for precise control of the wall thickness of the nanotubes. Using template-synthesized alumina nanotube films, we demonstrate a humidity sensor with a high response speed, a transmission electron microscopy (TEM) grid, and a catalyst support. The cross- stacked assembly, ultrathin thickness, chemical inertness, and high thermal stability of the alumina nanotube films contributed to the excellent performance of these devices. In addition, it is expected that the metal-oxide nanotube films would have significant potential owing to their material richness, macroscopic appearance, flexibility, compatibility with the semiconducting technologies, and the feasibility of mass production.展开更多
Here we review two 300℃metal–oxide(MO)thin-film transistor(TFT)technologies for the implementation of flexible electronic circuits and systems.Fluorination-enhanced TFTs for suppressing the variation and shift of tu...Here we review two 300℃metal–oxide(MO)thin-film transistor(TFT)technologies for the implementation of flexible electronic circuits and systems.Fluorination-enhanced TFTs for suppressing the variation and shift of turn-on voltage(VON),and dual-gate TFTs for acquiring sensor signals and modulating VON have been deployed to improve the robustness and performance of the systems in which they are deployed.Digital circuit building blocks based on fluorinated TFTs have been designed,fabricated,and characterized,which demonstrate the utility of the proposed low-temperature TFT technologies for implementing flexible electronic systems.The construction and characterization of an analog front-end system for the acquisition of bio-potential signals and an active-matrix sensor array for the acquisition of tactile images have been reported recently.展开更多
In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias tempe...In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias temperature(NBT)stressing under the particular pulsed bias. Particular values of the pulsed stress voltage frequency and duty cycle are chosen in order to analyze the recoverable and permanent components of stress-induced threshold voltage shift in detail. The results are discussed in terms of the mechanisms responsible for buildup of oxide charge and interface traps. The partial recovery during the low level of pulsed gate voltage is ascribed to the removal of recoverable component of degradation, i.e., to passivation/neutralization of shallow oxide traps that are not transformed into the deeper traps(permanent component).Considering the value of characteristic time constant associated with complete removal of the recoverable component of degradation, it is shown that by selecting an appropriate combination of the frequency and duty cycle, the threshold voltage shifts induced under the pulsed negative bias temperature stress conditions can be significantly reduced, which may be utilized for improving the device lifetime in real application circuits.展开更多
The paper proposes a novel transceiver in physical layer for high-speed serial data link based upon Universal Serial Bus (USB) 2.0, comprising transmitter and receiver. In the design, transmitter contains pre-and-main...The paper proposes a novel transceiver in physical layer for high-speed serial data link based upon Universal Serial Bus (USB) 2.0, comprising transmitter and receiver. In the design, transmitter contains pre-and-main driver to satisfy slew rate of output data, receiver includes optimized topology to improve preci- sion of received data. The circuit simulation is based on Cadence’s spectre software and Taiwan Semiconduc- tor Manufacture Corporation’s library of 0.25μm mixed-signal Complementary Metal-Oxide Semiconductor (CMOS) model. The front and post-simulation results reveal that the transceiver designed can transmit and re- ceive high-speed data in 480Mbps, which is in agreement with USB2.0 specification. The chip of physi- cal-layer transceiver has been designed and implemented with 0.25μm standard CMOS technology.展开更多
The resistive switching properties in amorphous Pr0.67Sr0.33MnO3 films deposited by pulsed laser deposition are investigated.Reproducible and bipolar counter-8-shape and 8-shape switching behaviours of Au/Pr0.67Sr0.33...The resistive switching properties in amorphous Pr0.67Sr0.33MnO3 films deposited by pulsed laser deposition are investigated.Reproducible and bipolar counter-8-shape and 8-shape switching behaviours of Au/Pr0.67Sr0.33MnO3 /F:SnO2 junctions are obtained at room temperature.Dramatically,the coexistence of two switching polarities could be reversibly adjusted by an applied voltage range.The results allocated those two switching types to areas of different defect densities beneath the same electrode.The migration of oxygen vacancies and the trapping effect of electrons under an applied electric field play an important role.An interface-effect-related resistance switching is proposed in an amorphous Pr0.67Sr0.33MnO3-based memory cell.展开更多
A unified charge-based model for fully depleted silicon-on-insulator (SOI) metal oxide semiconductor field-effect transistors (MOSFETs) is presented. The proposed model is accurate and applicable from intrinsic to...A unified charge-based model for fully depleted silicon-on-insulator (SOI) metal oxide semiconductor field-effect transistors (MOSFETs) is presented. The proposed model is accurate and applicable from intrinsic to heavily doped channels with various structure parameters. The framework starts from the one-dimensional Poisson Boltzmann equa- tion, and based on the full depletion approximation, an accurate inversion charge density equation is obtained. With the inversion charge density solution, the unified drain current expression is derived, and a unified terminal charge and intrinsic capacitance model is also derived in the quasi-static case. The validity and accuracy of the presented analytic model is proved by numerical simulations.展开更多
La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the ...La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the heterojunetions exhibit an asymmetric and resistance switching behaviour. A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy. The spatial homogeneity of the charge carrier distribution leads to field- induced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect. The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 x 10^4% by simulating the AC electric field. This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications.展开更多
To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffract...To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction ( XRD ), X-ray photoelectron spectroscopy ( XPS ) and scanning electron microscopy (SEM). The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer ( Zsimpwin ) combined with a potentiostate ( PAR 273). Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.展开更多
In the ultra-thin relaxed SiGe virtual substrates, a strained-Si channel p-type Metal Oxide Semiconductor Field Effect Transistor (p-MOSFET) is presented. Built on strained-Si/240nm relaxed-Si0.8 Ge0.2/ 100nm Low Temp...In the ultra-thin relaxed SiGe virtual substrates, a strained-Si channel p-type Metal Oxide Semiconductor Field Effect Transistor (p-MOSFET) is presented. Built on strained-Si/240nm relaxed-Si0.8 Ge0.2/ 100nm Low Temperature Si (LT-Si)/10nm Si buffer was grown by Molecular Beam Epitaxy (MBE), in which LT-Si layer is used to release stress of the SiGe layer and made it relaxed. Measurement indicates that the strained-Si p-MOSFET's (L=4.2μm) transconductance and the hole mobility are enhanced 30% and 50% respectively, compared with that of conventional bulk-Si. The maximum hole mobility for strained-Si device is 140cm2/Vs. The device performance is comparable to devices achieved on several μm thick composition graded buffers and relaxed-SiGe layer virtual substrates.展开更多
Modern scintillator-based radiation detectors require silicon photomultipliers(Si PMs)with photon detection efficiency higher than 40%at 420 nm,possibly extended to the vacuum ultraviolet(VUV)region,single-photon time...Modern scintillator-based radiation detectors require silicon photomultipliers(Si PMs)with photon detection efficiency higher than 40%at 420 nm,possibly extended to the vacuum ultraviolet(VUV)region,single-photon time resolution(SPTR)<100 ps,and dark count rate(DCR)<150 kcps/mm^(2).To enable single-photon time stamping,digital electronics and sensitive microcells need to be integrated in the same CMOS substrate,with a readout frame rate higher than 5 MHz for arrays extending over a total area up to 4 mm×4 mm.This is challenging due to the increasing doping concentrations at low CMOS scales,deep-level carrier generation in shallow trench isolation fabrication,and power consumption,among others.The advances at 350 and 110 nm CMOS nodes are benchmarked against available Si PMs obtained in CMOS and commercial customized technologies.The concept of digital multithreshold Si PMs with a single microcell readout is finally reported,proposing a possible direction toward fully digital scintillator-based radiation detectors.展开更多
基金supported by the Ministry of Science and Higher Education of the Russian Federation (Grant№075-15-2020-801)by Non-commercial Foundation for support of Science and Education 《INTELLECT》.
文摘Artificial synapses utilizing spike signals are essential elements of new generation brain-inspired computers.In this paper,we realize light-stimulated adaptive artificial synapse based on nanocrystalline zinc oxide film.The artificial synapse photoconductivity shows spike-type signal response,long and short-term memory(LTM and STM),STM-to-LTM transition and paired-pulse facilitation.It is also retaining the memory of previous exposures and demonstrates spike-frequency adaptation properties.A way to implement neurons with synaptic depression,tonic excitation,and delayed accelerating types of response under the influence of repetitive light signals is discussed.The developed artificial synapse is able to become a key element of neuromorphic chips and neuromorphic sensorics systems.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2010ZX02201)the National Natural Science Foundation of China (Grant No. 61176069)the National Defense Pre-Research of China (Grant No. 51308020304)
文摘A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge balance and suppresses the substrate-assisted depletion effect. Secondly, the new electric field peak produced by the P/P junction modulates the surface electric field distribution. Both of these result in a high breakdown voltage (BV). In addition, due to the same conduction paths, the specific on-resistance (Ron,sp) of the PD SJ-LDMOS is approximately identical to the conventional SJ-LDMOS. Simulation results indicate that the average value of the surface lateral electric field of the PD SJ-LDMOS reaches 20 V/μm at a 15 μm drift length, resulting in a BV of 300 V.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176092,61036003,and 60837001)the National Basic Research Program of China (Grant No. 2012CB933503)+1 种基金the Ph.D. Program Foundation of Ministry of Education of China (Grant No. 20110121110025)the Fundamental Research Funds for the Central Universities,China (Grant No. 2010121056)
文摘Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor (MOS) structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are characterized by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, capacitance-voltage (C-V) and current-voltage characteristics. It is demonstrated that wet thermal annealing at relatively higher temperature such as 550 ℃ can lead to Ge incorporation in HfO2 and the partial crystallization of HfO2, which should be responsible for the serious degradation of the electrical characteristics of the TaN/HfO2/Ge MOS capacitors. However, wet thermal annealing at 400 ℃ can decrease the GeOx interlayer thickness at the HfO2/Ge interface, resulting in a significant reduction of the interface states and a smaller effective oxide thickness, along with the introduction of a positive charge in the dielectrics due to the hydrolyzable property of GeOx in the wet ambient. The pre-growth of a thin GeO2 passivation layer can effectively suppress the interface states and improve the C V characteristics for the as-prepared HfO2 gated Ge MOS capacitors, but it also dissembles the benefits of wet thermal annealing to a certain extent.
基金Project supported by the National Natural Science Foundation of China(Grant No.51576100)the Project of"Six Talent Summit"of Jiangsu Province,China(Grant No.2014-XNY-002)
文摘This paper presents a numerical study on the simultaneous reconstruction of temperature and volume fraction fields of soot and metal-oxide nanoparticles in an axisymmetric nanofluid fuel sooting flame based on the radiative energy images captured by a charge-coupled device(CCD)camera.The least squares QR decomposition method was introduced to deal with the reconstruction inverse problem.The effects of ray numbers and measurement errors on the reconstruction accuracy were investigated.It was found that the reconstruction accuracies for volume fraction fields of soot and metaloxide nanoparticles were easily affected by the measurement errors for radiation intensity,whereas only the metal-oxide volume fraction field reconstruction was more sensitive to the measurement error for the volume fraction ratio of metaloxide nanoparticles to soot.The results show that the temperature,soot volume fraction,and metal-oxide nanoparticles volume fraction fields can be simultaneously and accurately retrieved for exact and noisy data using a single CCD camera.
基金supported by the Australian Research Council Discovery Project Funding Scheme(project number:DP180100568)
文摘Nanoclusters(NCs)have been demonstrated of outstanding performance in electrochemical energy storage and conversion technologies due to their strong quantum confinement effects and strong interaction with supports.Here,we developed a class of ultrafine metal-oxide(MOx,M=Fe,Co and Ni)NCs incorporated with iron phthalocyanine(FePc),MOx/FePc-G,supported on graphene as high-performance catalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and carbon dioxide reduction(CO2RR).The high activities for ORR and OER are attributed to the electron donation and accepting ability of the highly redox active of FePc-G that could tune the properties of MOx.The FeOx/FePc-G exhibits an extremely positive half-wave potential(E1/2)of 0.888 and 0.610 V for ORR in alkaline and neutral conditions,respectively,which is around 60 mV more positive than that of Pt/C.And NiOx/FePc-G shows similar OER activity with the state-of-the-art catalysts,Ir/C,and better performance than NiFeO NCs supported on graphene.Remarkably,the CoOx/FePc-G and NiOx/FePc-G show high activity and selectivity to reduce CO2 into CO with a low onset potential of-0.22 V(overpotential is 0.11 V).
基金This work was supported by China Postdoctoral Science Foundation under project number 2019M663054.
文摘Elecrochemical CO_(2) reduction is a promising route to convert CO_(2) into the value added chemicals,and to control the increasing accumulation of 002 in the atmosphere.The CO_(2) molecule is stable and chemically inert,so a highly efficient electrocatalyst is required for CO_(2) reduction.The single atoms with metal oxdde support is a new fronder in CO_(2) reduction.The supported single atoms contain disperse isolated atoms with an appropriate support maxcimize the atom efficiency of metals for boosting the catalytc perfomance.In this review,we had discussed state-of-the-art research on the synthestis of single atoms supported on the metal oxdde for boosting catalytic activity for CO_(2) reduction and special emphasis is placed on the influence of single atoms supported on metal oxdde on the CO_(2) reduction.Futhermore,we had discussed the challenges,and opportunities for paving the development of single atoms with metal support and their application in ecrocatalytic CO_(2) reduction.
基金supported by the National Key R&D Program of China(No.2022YFB4002401,2022YFB4003701)the National Natural Science Foundation of China(Nos.22178058,22308055)+2 种基金Science Fund for Creative Research Groups of the National Natural Science Foundation of China(22221005)Natural Science Foundation of Fujian Province(2022J05027)the Talent Program of Fuzhou University(XRC-22036).
文摘The ammonia decomposition for the production of carbon-free hydrogen has triggered great attention yet still remains challenging due to its sluggish kinetics,posting the importance of precise design of efficient catalysts for ammonia decomposition under low temperatures.Constructing the metal-support interaction and interface is one of the most important strategies for promoting catalysts.In this work,by coating ceria onto the Ni nanoparticles(NPs),we discover that the Ni-CeO_(2)interfaces create an exceptional effect to enhance the catalytic decomposition of ammonia by over 10 folds,compared with the pristine Ni.The kinetic analysis demonstrates that the recombinative N2 desorption is the rate-determining step(RDS)and the Ni-CeO_(2)interface greatly increases the RDS.Based on these understandings,a strategy to fabricate the Ni/CeO_(2)catalyst with abundant Ni-Ce-O interfaces via one-pot sol-gel method was employed(hereafter denoted to s-Ni/CeO_(2)).The s-Ni/CeO_(2)catalyst shows a high activity for ammonia decomposition,achieving a H_(2)formation rate of 10.5 mmol gcat1 min^(-1)at 550℃.Combined with a series of characterizations,the relationship between the catalyst structure and the performance was investigated for further understanding the effect of metal-oxide interfaces.
基金Project supported by the Fundamental Research Funds for the Central Universities(2232021G-10)。
文摘A series of multiphase metal-oxide catalysts(MnOx/γ-Al_(2)O_(3),CuOx/γ-Al_(2)O_(3),FeO_(x/γ)-Al_(2)O_(3),CeO_(x)/γ-Al_(2)O_(3)and LaOx/γ-Al_(2)O_(3))were prepared for plasma-catalyst degradation of multicomponent volatile organic compounds(VOCs,such as toluene,acetone and ethyl acetate).The results reveal that the degradation efficiency(DE)of acetone,toluene and ethyl acetate in the DDBD system can be arranged as follows:Mn_(2)O_(3)/γ-Al_(2)O_(3)>Fe2O3/γ-Al_(2)O_(3)>CuO_(/γ)-Al_(2)O_(3)>CeO_(2)/γ-Al_(2)O_(3)>La_(2)O_(3)/γ-Al_(2)O_(3)>γ-Al_(2)O_(3),and the highest DE(49.5%for acetone,93.3%for toluene and 79.8%for ethyl acetate)is obtained in Mn_(2)O_(3)/γ-Al_(2)O_(3)+double dielectric barrier discharge(DDBD)system at specific input energy(SIE)of 700 J/L.Compared with the other catalysts,Mn_(2)O_(3)/γ-Al_(2)O_(3)also exhibits the most significant inhibitory effect on the production of ozone(O3).On the other hand,CeO_(2)/γ-Al_(2)O_(3)and La_(2)O_(3)/γ-Al_(2)O_(3)catalysts display different catalytic selectivity.Both catalysts can slightly raise the DE of VOCs and remarkably facilitate VOCs’mineralization.The carbon balance(CB)is increased by 30.2%and 38.8%,and the CO_(2)selectivity(SCO_(2))is raised by 70.5%and 11.9%in the CeO_(2)/γ-Al_(2)O_(3)+DDBD system and La_(2)O_(3)/γ-Al_(2)O_(3)+DDBD system at SIE of 700 J/L,respectively.To further understand the catalytic effect of the catalysts,the adsorption of O3on different catalysts was simulated by a DFT model.According to the results of the DFT model,it is found that the adsorption energy of other metal oxides seems to be used as a reference for catalytic effect to a certain extent except CeO_(2).The higher the absolute values of adsorption energy,the higher the improvement of VOCs degradation efficiency by catalyst.
基金Supported by the National Nature Science Foundation of China (Grant Nos.50425721,5073001)the 11th Five-year National S&T Supporting Plan (Grant No.2006BAA02A16)
文摘The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51706141 and 51976122)。
文摘With the growing applications of nanofluid flame, the monitoring and controlling of its combustion process is of paramount importance. Thus, it is necessary to develop diagnosing methods which can simultaneously image important parameters such as temperature and volume fractions of soot, metal-oxide nanoparticles. Tomographic emission spectroscopy is an effective method which has been proposed for this purpose. However, the inversion process was only reported with least-squares QR decomposition(LSQR) so far and there are numerous well-established reconstruction algorithms which have not been utilized yet.Thus, this work aims to perform systematic comparative studies on several representative algorithms for the inversion process. In the simulative studies, algorithms including Tikhonov regularization, algebraic reconstruction technique(ART), LSQR,Landweber algorithm, maximum likelihood expectation maximization(MLEM), and ordered subset expectation maximization(OSEM) were discussed. The effects of the number of iterations, the signal-to-noise ratio, and the number of projections and the calibration error in projection angles on the performance of the algorithms were investigated. Advice on selecting the suitable algorithms under different application conditions is then provided according to the extensive numerical studies.
基金This work was supported by the National Basic Research Program of China (No. 2012CB932301), the National Natural Science Foundation of China (Nos. 51472142, 51102147, and 51102144), and the Chinese Postdoctoral Science Foundation (Nos. 2014M550701 and 2012M520261).
文摘Aligned carbon nanotube films coated with amorphous carbon were developed into novel templates by atomic layer deposition. Freestanding macroscopic metal-oxide nanotube films were then successfully synthesized by using these templates. The reactive amorphous carbon layer greatly improved the nuclei density, which ensured the high quality of the films and allowed for precise control of the wall thickness of the nanotubes. Using template-synthesized alumina nanotube films, we demonstrate a humidity sensor with a high response speed, a transmission electron microscopy (TEM) grid, and a catalyst support. The cross- stacked assembly, ultrathin thickness, chemical inertness, and high thermal stability of the alumina nanotube films contributed to the excellent performance of these devices. In addition, it is expected that the metal-oxide nanotube films would have significant potential owing to their material richness, macroscopic appearance, flexibility, compatibility with the semiconducting technologies, and the feasibility of mass production.
基金supported by Grant RGC 16215720 from the Science and Technology Program of Shenzhen under JCYJ20200109140601691Grant GHP/018/21SZ from the Innovation and Technology Fund+1 种基金Grant SGDX20211123145404006 from the Science and Technology Program of ShenzhenFundamental and Applied Fundamental Research Fund of Guangdong Province 2021B1515130001。
文摘Here we review two 300℃metal–oxide(MO)thin-film transistor(TFT)technologies for the implementation of flexible electronic circuits and systems.Fluorination-enhanced TFTs for suppressing the variation and shift of turn-on voltage(VON),and dual-gate TFTs for acquiring sensor signals and modulating VON have been deployed to improve the robustness and performance of the systems in which they are deployed.Digital circuit building blocks based on fluorinated TFTs have been designed,fabricated,and characterized,which demonstrate the utility of the proposed low-temperature TFT technologies for implementing flexible electronic systems.The construction and characterization of an analog front-end system for the acquisition of bio-potential signals and an active-matrix sensor array for the acquisition of tactile images have been reported recently.
基金Project supported by the Fund from the Ministry of Education,Science and Technological Development of the Republic of Serbia(Grant Nos.OI-171026 and TR-32026)the Ei PCB Factory,Ni
文摘In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias temperature(NBT)stressing under the particular pulsed bias. Particular values of the pulsed stress voltage frequency and duty cycle are chosen in order to analyze the recoverable and permanent components of stress-induced threshold voltage shift in detail. The results are discussed in terms of the mechanisms responsible for buildup of oxide charge and interface traps. The partial recovery during the low level of pulsed gate voltage is ascribed to the removal of recoverable component of degradation, i.e., to passivation/neutralization of shallow oxide traps that are not transformed into the deeper traps(permanent component).Considering the value of characteristic time constant associated with complete removal of the recoverable component of degradation, it is shown that by selecting an appropriate combination of the frequency and duty cycle, the threshold voltage shifts induced under the pulsed negative bias temperature stress conditions can be significantly reduced, which may be utilized for improving the device lifetime in real application circuits.
文摘The paper proposes a novel transceiver in physical layer for high-speed serial data link based upon Universal Serial Bus (USB) 2.0, comprising transmitter and receiver. In the design, transmitter contains pre-and-main driver to satisfy slew rate of output data, receiver includes optimized topology to improve preci- sion of received data. The circuit simulation is based on Cadence’s spectre software and Taiwan Semiconduc- tor Manufacture Corporation’s library of 0.25μm mixed-signal Complementary Metal-Oxide Semiconductor (CMOS) model. The front and post-simulation results reveal that the transceiver designed can transmit and re- ceive high-speed data in 480Mbps, which is in agreement with USB2.0 specification. The chip of physi- cal-layer transceiver has been designed and implemented with 0.25μm standard CMOS technology.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60976016)the Program for Innovative Research Team in Science and Technology in University of Henan Province (IRTSTUHN),China (Grant No. 2012IRTSTHN004)the Foundation Co-established by the Province and the Ministry in Henan University,China (Grant No. SBGJ090503)
文摘The resistive switching properties in amorphous Pr0.67Sr0.33MnO3 films deposited by pulsed laser deposition are investigated.Reproducible and bipolar counter-8-shape and 8-shape switching behaviours of Au/Pr0.67Sr0.33MnO3 /F:SnO2 junctions are obtained at room temperature.Dramatically,the coexistence of two switching polarities could be reversibly adjusted by an applied voltage range.The results allocated those two switching types to areas of different defect densities beneath the same electrode.The migration of oxygen vacancies and the trapping effect of electrons under an applied electric field play an important role.An interface-effect-related resistance switching is proposed in an amorphous Pr0.67Sr0.33MnO3-based memory cell.
基金supported by the National Natural Science Foundation of China (Grant No. 60876027)the State Key Program of the National Natural Science Foundation of China (Grant No. 61036004)+2 种基金the Shenzhen Science and Technology Foundation, China (Grant No. CXB201005250031A)the Fundamental Research Project of Shenzhen Science and Technology Foundation, China (Grant No. JC201005280670A)the International Collaboration Project of Shenzhen Science & Technology Foundation, China (Grant No. ZYA2010006030006A)
文摘A unified charge-based model for fully depleted silicon-on-insulator (SOI) metal oxide semiconductor field-effect transistors (MOSFETs) is presented. The proposed model is accurate and applicable from intrinsic to heavily doped channels with various structure parameters. The framework starts from the one-dimensional Poisson Boltzmann equa- tion, and based on the full depletion approximation, an accurate inversion charge density equation is obtained. With the inversion charge density solution, the unified drain current expression is derived, and a unified terminal charge and intrinsic capacitance model is also derived in the quasi-static case. The validity and accuracy of the presented analytic model is proved by numerical simulations.
基金supported by the National Natural Science Foundation of China (Grant No. 60976016)the Program for Innovative Research Team in Science and Technology in University of Henan Province (IRTSTHN),China (Grant No. 2012IRTSTHN004)the Research Program of Henan University, China (Grant No. SBGJ090503)
文摘La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the heterojunetions exhibit an asymmetric and resistance switching behaviour. A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy. The spatial homogeneity of the charge carrier distribution leads to field- induced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect. The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 x 10^4% by simulating the AC electric field. This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications.
基金Funded by Guangdong Provincial Natural Science Foundation ofChina(No.06300397) and Director Foundation of South China Ag-ricultural University (No.K06143)
文摘To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction ( XRD ), X-ray photoelectron spectroscopy ( XPS ) and scanning electron microscopy (SEM). The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer ( Zsimpwin ) combined with a potentiostate ( PAR 273). Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.
文摘In the ultra-thin relaxed SiGe virtual substrates, a strained-Si channel p-type Metal Oxide Semiconductor Field Effect Transistor (p-MOSFET) is presented. Built on strained-Si/240nm relaxed-Si0.8 Ge0.2/ 100nm Low Temperature Si (LT-Si)/10nm Si buffer was grown by Molecular Beam Epitaxy (MBE), in which LT-Si layer is used to release stress of the SiGe layer and made it relaxed. Measurement indicates that the strained-Si p-MOSFET's (L=4.2μm) transconductance and the hole mobility are enhanced 30% and 50% respectively, compared with that of conventional bulk-Si. The maximum hole mobility for strained-Si device is 140cm2/Vs. The device performance is comparable to devices achieved on several μm thick composition graded buffers and relaxed-SiGe layer virtual substrates.
基金supported by the National Natural Science Foundation of China(Nos.62250002,62027808,and 62027801)the Sino-German Mobility Programme(No.M-0387)。
文摘Modern scintillator-based radiation detectors require silicon photomultipliers(Si PMs)with photon detection efficiency higher than 40%at 420 nm,possibly extended to the vacuum ultraviolet(VUV)region,single-photon time resolution(SPTR)<100 ps,and dark count rate(DCR)<150 kcps/mm^(2).To enable single-photon time stamping,digital electronics and sensitive microcells need to be integrated in the same CMOS substrate,with a readout frame rate higher than 5 MHz for arrays extending over a total area up to 4 mm×4 mm.This is challenging due to the increasing doping concentrations at low CMOS scales,deep-level carrier generation in shallow trench isolation fabrication,and power consumption,among others.The advances at 350 and 110 nm CMOS nodes are benchmarked against available Si PMs obtained in CMOS and commercial customized technologies.The concept of digital multithreshold Si PMs with a single microcell readout is finally reported,proposing a possible direction toward fully digital scintillator-based radiation detectors.