Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In2Se3and MoS2were t...Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In2Se3and MoS2were transferred to the substrate by the mechanical exfoliation method, then a heterojunction MoS_(2)/α-In_(2)Se_(3) memtransistor was prepared. Neural synaptic simulations were performed using electrical and optical pulses as input signals. Through measurements, such as excitatory/inhibitory post-synaptic current(EPSC/IPSC), long-term potentiation/depression(LTP/LTD), and paired-pulse facilitation/depression(PPF/PPD), it can be found that the fabricated device could simulate various functions of neural synapses well, and could work as an electronic synapse in artificial neural networks, proposing a possible solution for neuromorphic storage and computation.展开更多
An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-lockin...An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-locking method. The steady-state probability distribution, the mean light intensity, the normalization autocorrelation function, and cross correlation function are calculated. The results indicate that： （i） The cross-correlation between the real and imaginary parts of quantum noise can cause the stationary probability distribution from one peak structure to two extrema structure when the laser system is operated above threshold; （ii） The cross-correlation between the real and imaginary parts of quantum noise enhance the light intensity fluctuation and decrease the laser output when the laser system is operated below or near threshold; （iii） The effect of the cross-correlation between the real and imaginary parts of quantum noise is very weak on the stationary properties when the laser system is operated far above threshold.展开更多
This paper investigates the two-time intensity correlation function of a two-mode ring laser system subjected to both pump and quantum noises by stochastic simulation. It finds that the decay rate of the intensity cor...This paper investigates the two-time intensity correlation function of a two-mode ring laser system subjected to both pump and quantum noises by stochastic simulation. It finds that the decay rate of the intensity correlation function of one mode gets faster with decreasing values of relevant parameters, i.e., the coupling constant ξ, the cross-correlation coefficient A, the difference of the pump parameters Aa and the pump parameter al; however, its variations get complex in the other mode when relevant parameters are changed. The investigating results also show that the effects of the mode competition on intensity correlation function are obvious.展开更多
Electrochemical detection is an efficient method for the detection of Bisphenol A(BPA).Herein,a sensitive photo-electrochemical sensor based on two-dimensional(2 D)TiO_(2)(001)nanosheets was fabricated and then used f...Electrochemical detection is an efficient method for the detection of Bisphenol A(BPA).Herein,a sensitive photo-electrochemical sensor based on two-dimensional(2 D)TiO_(2)(001)nanosheets was fabricated and then used for BPA electrochemical detection.Upon light irradiation,the 2 D TiO_(2)(001)nanosheets electrode provided a lower detection limit of BPA detection compared with an ambient electrochemical determination.The low detection limit is^5.37 nmol/L(S/N=3).Furthermore,profiting from the photoelectric characteristics,the 2 D TiO_(2)(001)nanosheets electrode exhibits a nice regeneration prope rty.After 45 min of light irradiation,the electrochemical signal was regenerated from14.7%to 82.9%of the original signal at the 6th cycle.This is attributed to the non-selective·OH mediation produced by the 2 D TiO_(2)(001)nanosheets mineralizing anodic polymeric products and resuming surface reactive sites.This investigation indicates that photo-assistance is an efficient method to improve the electrochemical sensor for detecting BPA in water environments.展开更多
The asymmetric effects on the escape rates from the stable states x±in the bistable system are analyzed. The results indicate that the multiplicative noise and the additive noise always enhance the particle escap...The asymmetric effects on the escape rates from the stable states x±in the bistable system are analyzed. The results indicate that the multiplicative noise and the additive noise always enhance the particle escape from stable states x±of bistable.However,the asymmetric parameter r enhances the particle escape from stable state x_+,and holds back the particle escape from stable state x_-.展开更多
To study the nonlinear phenomena in rod-like magnetic liquid crystals(RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic fi...To study the nonlinear phenomena in rod-like magnetic liquid crystals(RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic field.We find the twist of the molecules under magnetic field can be propagated in the form of a traveling wave. The dynamic equation of the molecular twisting we derived satisfies the form of Sine-Gordon equation. We obtain two solutions of the Sine-Gordon equation by theoretical calculation: the kink and anti-kink solitons and breathers. The characteristics of those solitons and breathers are discussed.展开更多
A design of ultrathin crystalline silicon solar cell with Si_(3)N_(4)circular truncated cone holes(CTCs)arrays on the top is proposed.In this article,we perform an optical simulation of the structure.The finite-differ...A design of ultrathin crystalline silicon solar cell with Si_(3)N_(4)circular truncated cone holes(CTCs)arrays on the top is proposed.In this article,we perform an optical simulation of the structure.The finite-difference time-domain method is used to calculate the optical absorption of different periods,radius of top and bottom circles and depth of Si_(3)N_(4)CTCs.The short-circuit current density generated by the optimized cells(30.17 mA/cm^2)is 32.44%more than the value gained by control group(with flat Si_(3)N_(4)).Then adding a layer of back silver to allow us to better analyze optical absorption.Later,we simulate the optimization of the same configuration of different silicon thicknesses andfind that our structure does enhance the light absorption.This work uses a combined path towards achieving higher photocurrent ultrathin crystalline silicon solar cells by constructing the texture of anti-reflection coating.展开更多
A GaAs metal-oxide-semiconductor （MOS） capacitor with HfO2 as gate dielectric and silicon nitride （SiNx） as the interlayer （IL） is fabricated. Experimental results show that the sample with the SiNx IL has an im...A GaAs metal-oxide-semiconductor （MOS） capacitor with HfO2 as gate dielectric and silicon nitride （SiNx） as the interlayer （IL） is fabricated. Experimental results show that the sample with the SiNx IL has an improved capacitance- voltage characteristic, lower leakage current density （0.785 × 10^-6 Alcm^2 at Vfo ＋ 1 V） and lower interface-state density （2.9 × 10^12 eV^-1 ·cm^-2） compared with other samples with N2- or NH3-plasma pretreatment. The influences of post- deposition annealing temperature on electrical properties are also investigated for the samples with SiNx IL. The sample annealed at 600 ℃ exhibits better electrical properties than that annealed at 500 ℃, which is attributed to the suppression of native oxides, as confirmed by XPS analyses.展开更多
Real-time monitoring of the Bragg peak location of carbon ions is urgently required for the quality control of hadron therapy. In this study, we design an annular detector to monitor the Bragg peak location of carbon ...Real-time monitoring of the Bragg peak location of carbon ions is urgently required for the quality control of hadron therapy. In this study, we design an annular detector to monitor the Bragg peak location of carbon ions with Geant4 simulation. This 360° surrounding structure has a high detection efficiency for the small-dose situation. The detector consists of a multilayered collimator system and an Na I scintillator for prompt gamma counting. The multilayered collimator includes a lead layer to prevent unwanted gammas and the paraffin and boron carbide layers to moderate and capture fast neutrons. An inclination of the detector further diminishes the background signal caused by neutrons. The detector, with optimized parameters, is applicable to carbon ions of different energies. In addition, the scintillator is replaced by an improved EJ301 organic liquid scintillator to discriminate gammas and neutrons. Inserting thin Fe slices into the liquid scintillator improves the energy deposition efficiency. The Bragg peak location of 200 Me V/u carbon ions can be monitored by prompt gamma detection with the improved liquid scintillator.展开更多
To date, many efforts have been made to improve the performance of paintable carbon-based （PC-based） perovskite solar cells （PSCs）. Though great progress has been achieved, their power conversion efficiencies are ...To date, many efforts have been made to improve the performance of paintable carbon-based （PC-based） perovskite solar cells （PSCs）. Though great progress has been achieved, their power conversion efficiencies are still relatively low compared with hole-transport-materials-based PSCs. General research on influencing factors of performance in PC-based PSCs is still insufficient. In this work, PC-based PSCs were fabricated in ambient air and four groups of controlled experi- ments were performed in which the PbI2 layers were prepared with or without antisolvent extraction treatment. These four groups of experiments were designed to find out the effect of different influencing factors on PC-based PSCs performance, for example, PbI2 residual, the surface morphology of the perovskite film, the surface roughness of the perovskite film, and the contact status of the perovskite/carbon electrode interface. With a systematic analysis, we demonstrated that the contact status of the perovskite/carbon electrode interface played a vital role in PC-based PSCs, and a fiat, smooth perovskite surface could help to improve this contact status significantly. Besides, on the precondition of a poor contact interface, no PbI2 residual and a good surface morphology only brought limited benefits to the performances of PC-based PSCs.展开更多
The propagation of dust ion-acoustic wave in an inhomogeneous dusty plasma is studied by taking the dust charge fluctuation and collisions into account. It is shown that the dust charge fluctuation brings a phase shif...The propagation of dust ion-acoustic wave in an inhomogeneous dusty plasma is studied by taking the dust charge fluctuation and collisions into account. It is shown that the dust charge fluctuation brings a phase shift to the wave. Furthermore, because of the presence of dust charge fluctuation, a new damping term rises, which makes the damping more sharply.展开更多
The exceptional resistive switching characteristics and neuromorphic computational potential of memristors are crucial for advancing information processing in both traditional and non-traditional computing paradigms.H...The exceptional resistive switching characteristics and neuromorphic computational potential of memristors are crucial for advancing information processing in both traditional and non-traditional computing paradigms.However,the non-ideal resistive switching behavior of conventional oxide-based memristors hardly meets the performance requirements for neuromorphic computing applications.Besides,the two-terminal memristors are restricted by their configuration limitations toward multifield/multi-functional modulation.Herein,this article presents a 2D GaSe/MoS_(2) heterojunction thin-film transistor with four-terminal(4-T)tuning capability and flexible programming/erasing operations for non-volatile storage.res.展开更多
Mercury cadmium telluride films were grown by the RF magnetron sputtering technique at different sputtering powers.In experiment,X-ray diffraction（XRD） and atomic force microscopy（AFM） have been used to characteri...Mercury cadmium telluride films were grown by the RF magnetron sputtering technique at different sputtering powers.In experiment,X-ray diffraction（XRD） and atomic force microscopy（AFM） have been used to characterize the microstructure of HgCdTe films.The experimental results showed that when the growth power increased,the growth rate of HgCdTe films increased;when the growth power was less than 30 W,the HgCdTe film deposited by RF magnetron sputtering was amorphous;when the growth power was more than 30 W,the films exhibited polycrystalline structure.Films deposited at different growth rates were found to have characteristically different formations and surface morphologies;as observed through AFM,the surface morphology is composed of longitudinal islands forming a maze-like pattern in the high deposition rate.AFM analysis also illustrated that a significant reduction in the areal density of large islands and characteristically smoother films was achieved using a low deposition rate.展开更多
Based on the electromagnetic theory and by using an analytical technique-the transfer matrix method, the obliquely incident electromagnetic waves propagating in one-dimension plasma photonic crystals is studied. The d...Based on the electromagnetic theory and by using an analytical technique-the transfer matrix method, the obliquely incident electromagnetic waves propagating in one-dimension plasma photonic crystals is studied. The dispersion relations for both the P-polarization waves and S-polarization waves, depending on the plasma density, plasma thickness and period, are discussed.展开更多
Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated pho...Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated phototransistor based on the vertical HfSe_(2)/MoS_(2)heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse.Under bias,the phototransistor exhibits high responsivity of up to 1.42×103A/W,and ultrahigh specific detectivity of up to 1.39×1015cm·Hz^(1/2)·W^(-1).Moreover,it can also operate under zero bias with remarkable responsivity of 10.2 A/W,relatively high specific detectivity of 1.43×1014cm·Hz^(1/2)·W^(-1),ultralow dark current of 1.22 f A,and high on/off ratio of above 105.These results should be attributed to the fact that the vertical HfSe_(2)/MoS_(2)heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity.Therefore,the heterostructure provides a promising candidate for next generation high performance phototransistors.展开更多
GaAs metal–oxide–semiconductor（MOS） capacitors with HfTiO as the gate dielectric and Al2O3 or ZnO as the interface passivation layer（IPL） are fabricated. X-ray photoelectron spectroscopy reveals that the Al2O3 I...GaAs metal–oxide–semiconductor（MOS） capacitors with HfTiO as the gate dielectric and Al2O3 or ZnO as the interface passivation layer（IPL） are fabricated. X-ray photoelectron spectroscopy reveals that the Al2O3 IPL is more effective in suppressing the formation of native oxides and As diffusion than the ZnO IPL. Consequently, experimental results show that the device with Al2O3 IPL exhibits better interfacial and electrical properties than the device with ZnO IPL： lower interface-state density（7.2×10^12 eV1cm^2/, lower leakage current density（3.60×10^7A/cm^2 at Vg D1 V） and good C–V behavior.展开更多
Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect ...Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect band gap. In this paper, we investigate the suitability of surface plasmon resonance Ag nanoparticles for enhancing optical absorption in the thin film solar cell. For evaluating the transmittance capability of Ag nanoparticles and the conventional antireflection film, an enhanced transmittance factor is introduced. We find that under the solar spectrum AM1.5, the transmittance of Ag nanoparticles with radius over 160 nm is equivalent to that of conventional textured antireflection film, and its effect is better than that of the planar antireflection film. The influence of the surrounding medium is also discussed.展开更多
In this study we consider the boundary estimation of annular two-phase flow in a pipe with the potential distribution on the electrodes mounted on the outer boundary of the pipe, by taking use of electrical impedance ...In this study we consider the boundary estimation of annular two-phase flow in a pipe with the potential distribution on the electrodes mounted on the outer boundary of the pipe, by taking use of electrical impedance tomography (EIT) technique with the numerical solution obtained from an improved boundary distributed source (IBDS) method. The particle swarm optimization (PSO) is used to iteratively seek the boundary configuration. The simulation results showed that PSO and EIT technique with numerical solution obtained from IBDS has been successfully applied to the monitoring of an annular two-phase flow.展开更多
CsPbI_(3)perovskites with suitable bandgaps∼1.70 eV present distinct advantages for top-cell photovoltaic materials in tandem solar cells,however,relevant work has been rarely reported.This work designed a sandwich-l...CsPbI_(3)perovskites with suitable bandgaps∼1.70 eV present distinct advantages for top-cell photovoltaic materials in tandem solar cells,however,relevant work has been rarely reported.This work designed a sandwich-like MoO_(X)/Ag/MoO_(X)(MAM)buffer layer as the front cell window layer to maximize incident light utilization efficiency for semi-transparent CsPbI_(3)solar cells and four terminal(4-T)stacked cells.Further investigation revealed that the MAM has to experience in-situ reaction between Ag metal and fresh MoO_(X),which can simultaneously ensure the transparency of the buffer layer and improve the carrier transportation and collection,except for protecting the underlying spiro-OMeTAD layer from the bombardment of magnetron sputtering.Thanks to this MAM buffer layer and a tunnel oxide passivating contact(TOPCon)bottom cell with edge passivation,semi-transparent CsPbI_(3)devices(aperture area:0.50 cm^(2))demonstrated a power conversion efficiency(PCE)of 18.86%while corresponding 4-T CsPbI_(3)/TOPCon tandem solar cells(PSTSCs)presented the PCE of 26.55%.Besides,we also fabricated semi-transparent CsPbI_(3)minimodules with 16.67%PCE and 4-T PSTSCs with 26.41%PCE(aperture area:6.62 cm^(2)).This work provided a new scalable strategy for transparent buffer layers by constructing in-situ generated sandwich structured buffer layer,which is suitable for perovskite tandem solar cells.展开更多
Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidatio...Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidation stage is dominated by the dislocation-mediated oxidation behavior of Cu2O NCs via solid-solid transformations, leading to the formation of a new intermediate CuOx phase. The possible crystal structure of the CuOx phase is discussed. （2） Subsequently, CuOx is transformed into CuO by layer-by-layer oxidation. These results will help in understanding the oxidation mechanisms of copper oxides and pave the way for improving their structural diversity and exploiting their potential industrial applications.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 51702245)。
文摘Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In2Se3and MoS2were transferred to the substrate by the mechanical exfoliation method, then a heterojunction MoS_(2)/α-In_(2)Se_(3) memtransistor was prepared. Neural synaptic simulations were performed using electrical and optical pulses as input signals. Through measurements, such as excitatory/inhibitory post-synaptic current(EPSC/IPSC), long-term potentiation/depression(LTP/LTD), and paired-pulse facilitation/depression(PPF/PPD), it can be found that the fabricated device could simulate various functions of neural synapses well, and could work as an electronic synapse in artificial neural networks, proposing a possible solution for neuromorphic storage and computation.
基金Supported by the National Natural Science Foundation of China under Grant No.10865006
文摘An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-locking method. The steady-state probability distribution, the mean light intensity, the normalization autocorrelation function, and cross correlation function are calculated. The results indicate that： （i） The cross-correlation between the real and imaginary parts of quantum noise can cause the stationary probability distribution from one peak structure to two extrema structure when the laser system is operated above threshold; （ii） The cross-correlation between the real and imaginary parts of quantum noise enhance the light intensity fluctuation and decrease the laser output when the laser system is operated below or near threshold; （iii） The effect of the cross-correlation between the real and imaginary parts of quantum noise is very weak on the stationary properties when the laser system is operated far above threshold.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10865006)the Natural Science Foundation of Yunnan Province of China (Grant No. 2005A0002M)
文摘This paper investigates the two-time intensity correlation function of a two-mode ring laser system subjected to both pump and quantum noises by stochastic simulation. It finds that the decay rate of the intensity correlation function of one mode gets faster with decreasing values of relevant parameters, i.e., the coupling constant ξ, the cross-correlation coefficient A, the difference of the pump parameters Aa and the pump parameter al; however, its variations get complex in the other mode when relevant parameters are changed. The investigating results also show that the effects of the mode competition on intensity correlation function are obvious.
基金the Applied Basic Research Programs of Yunnan Science and Technology Department(No.2017FD085)the Program of Introducing Talents of Kunming University(Nos.YJL16003 and YJL18008)+4 种基金National Nature Science Foundation of China(No.61904073)Science Foundation of Yunnan Provincial Education Department(No.2018JS392)Projects of Science and Technology Plans of Kunming(No.20191-C-25318000002189)“Thousand Talents Program”of Yunnan Province for Young TalentsSpring City Plan-Special Program for Young Talents。
文摘Electrochemical detection is an efficient method for the detection of Bisphenol A(BPA).Herein,a sensitive photo-electrochemical sensor based on two-dimensional(2 D)TiO_(2)(001)nanosheets was fabricated and then used for BPA electrochemical detection.Upon light irradiation,the 2 D TiO_(2)(001)nanosheets electrode provided a lower detection limit of BPA detection compared with an ambient electrochemical determination.The low detection limit is^5.37 nmol/L(S/N=3).Furthermore,profiting from the photoelectric characteristics,the 2 D TiO_(2)(001)nanosheets electrode exhibits a nice regeneration prope rty.After 45 min of light irradiation,the electrochemical signal was regenerated from14.7%to 82.9%of the original signal at the 6th cycle.This is attributed to the non-selective·OH mediation produced by the 2 D TiO_(2)(001)nanosheets mineralizing anodic polymeric products and resuming surface reactive sites.This investigation indicates that photo-assistance is an efficient method to improve the electrochemical sensor for detecting BPA in water environments.
基金Supported by the Natural Science Foundation of China under Grant No.10865006the Natural Science Foundation of Shaanxi Province under Grant No.2010JQ1014the Science Foundation of Baoji University of Science and Arts of China under Grant No.ZK0954
文摘The asymmetric effects on the escape rates from the stable states x±in the bistable system are analyzed. The results indicate that the multiplicative noise and the additive noise always enhance the particle escape from stable states x±of bistable.However,the asymmetric parameter r enhances the particle escape from stable state x_+,and holds back the particle escape from stable state x_-.
基金Supported by the Basic Scientific Research Project of Provincial Colleges and Universities in Heilongjiang Province under Grant No.KJCXZD201723the Youth Science Foundations of Heilongjiang University under Grant No.QL201606
文摘To study the nonlinear phenomena in rod-like magnetic liquid crystals(RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic field.We find the twist of the molecules under magnetic field can be propagated in the form of a traveling wave. The dynamic equation of the molecular twisting we derived satisfies the form of Sine-Gordon equation. We obtain two solutions of the Sine-Gordon equation by theoretical calculation: the kink and anti-kink solitons and breathers. The characteristics of those solitons and breathers are discussed.
基金Project supported by National Science Foundation of China(NSFC)(U1765105,61604087)The Hebei Provincial Young Top-notch Talent Support Program(BJRC2013)Alexander von Humboldt-Stiftung(AUS-1141939-HFST-E)
文摘A design of ultrathin crystalline silicon solar cell with Si_(3)N_(4)circular truncated cone holes(CTCs)arrays on the top is proposed.In this article,we perform an optical simulation of the structure.The finite-difference time-domain method is used to calculate the optical absorption of different periods,radius of top and bottom circles and depth of Si_(3)N_(4)CTCs.The short-circuit current density generated by the optimized cells(30.17 mA/cm^2)is 32.44%more than the value gained by control group(with flat Si_(3)N_(4)).Then adding a layer of back silver to allow us to better analyze optical absorption.Later,we simulate the optimization of the same configuration of different silicon thicknesses andfind that our structure does enhance the light absorption.This work uses a combined path towards achieving higher photocurrent ultrathin crystalline silicon solar cells by constructing the texture of anti-reflection coating.
基金supported by the National Natural Science Foundation of China (Grant No. 61176100)
文摘A GaAs metal-oxide-semiconductor （MOS） capacitor with HfO2 as gate dielectric and silicon nitride （SiNx） as the interlayer （IL） is fabricated. Experimental results show that the sample with the SiNx IL has an improved capacitance- voltage characteristic, lower leakage current density （0.785 × 10^-6 Alcm^2 at Vfo ＋ 1 V） and lower interface-state density （2.9 × 10^12 eV^-1 ·cm^-2） compared with other samples with N2- or NH3-plasma pretreatment. The influences of post- deposition annealing temperature on electrical properties are also investigated for the samples with SiNx IL. The sample annealed at 600 ℃ exhibits better electrical properties than that annealed at 500 ℃, which is attributed to the suppression of native oxides, as confirmed by XPS analyses.
基金supported by the National Natural Science Foundation of China(Nos.11375073 and U1232206)
文摘Real-time monitoring of the Bragg peak location of carbon ions is urgently required for the quality control of hadron therapy. In this study, we design an annular detector to monitor the Bragg peak location of carbon ions with Geant4 simulation. This 360° surrounding structure has a high detection efficiency for the small-dose situation. The detector consists of a multilayered collimator system and an Na I scintillator for prompt gamma counting. The multilayered collimator includes a lead layer to prevent unwanted gammas and the paraffin and boron carbide layers to moderate and capture fast neutrons. An inclination of the detector further diminishes the background signal caused by neutrons. The detector, with optimized parameters, is applicable to carbon ions of different energies. In addition, the scintillator is replaced by an improved EJ301 organic liquid scintillator to discriminate gammas and neutrons. Inserting thin Fe slices into the liquid scintillator improves the energy deposition efficiency. The Bragg peak location of 200 Me V/u carbon ions can be monitored by prompt gamma detection with the improved liquid scintillator.
基金Project supported by the National Natural Science Foundation of China(Grant No.51702245)the Fundamental Research Funds for the Central Universities,China(Grant No.WUT:2017IB013)
文摘To date, many efforts have been made to improve the performance of paintable carbon-based （PC-based） perovskite solar cells （PSCs）. Though great progress has been achieved, their power conversion efficiencies are still relatively low compared with hole-transport-materials-based PSCs. General research on influencing factors of performance in PC-based PSCs is still insufficient. In this work, PC-based PSCs were fabricated in ambient air and four groups of controlled experi- ments were performed in which the PbI2 layers were prepared with or without antisolvent extraction treatment. These four groups of experiments were designed to find out the effect of different influencing factors on PC-based PSCs performance, for example, PbI2 residual, the surface morphology of the perovskite film, the surface roughness of the perovskite film, and the contact status of the perovskite/carbon electrode interface. With a systematic analysis, we demonstrated that the contact status of the perovskite/carbon electrode interface played a vital role in PC-based PSCs, and a fiat, smooth perovskite surface could help to improve this contact status significantly. Besides, on the precondition of a poor contact interface, no PbI2 residual and a good surface morphology only brought limited benefits to the performances of PC-based PSCs.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40244006 and 10475075, and the Youth Foundation of China University of Mining and Technology （0K4484）.
文摘The propagation of dust ion-acoustic wave in an inhomogeneous dusty plasma is studied by taking the dust charge fluctuation and collisions into account. It is shown that the dust charge fluctuation brings a phase shift to the wave. Furthermore, because of the presence of dust charge fluctuation, a new damping term rises, which makes the damping more sharply.
基金supported by the National Natural Science Foundation of China(52273231)the National Natural Science Foundation of China(52127816)。
文摘The exceptional resistive switching characteristics and neuromorphic computational potential of memristors are crucial for advancing information processing in both traditional and non-traditional computing paradigms.However,the non-ideal resistive switching behavior of conventional oxide-based memristors hardly meets the performance requirements for neuromorphic computing applications.Besides,the two-terminal memristors are restricted by their configuration limitations toward multifield/multi-functional modulation.Herein,this article presents a 2D GaSe/MoS_(2) heterojunction thin-film transistor with four-terminal(4-T)tuning capability and flexible programming/erasing operations for non-volatile storage.res.
基金supported by the National Natural Science Foundation of China(No.60576069).
文摘Mercury cadmium telluride films were grown by the RF magnetron sputtering technique at different sputtering powers.In experiment,X-ray diffraction（XRD） and atomic force microscopy（AFM） have been used to characterize the microstructure of HgCdTe films.The experimental results showed that when the growth power increased,the growth rate of HgCdTe films increased;when the growth power was less than 30 W,the HgCdTe film deposited by RF magnetron sputtering was amorphous;when the growth power was more than 30 W,the films exhibited polycrystalline structure.Films deposited at different growth rates were found to have characteristically different formations and surface morphologies;as observed through AFM,the surface morphology is composed of longitudinal islands forming a maze-like pattern in the high deposition rate.AFM analysis also illustrated that a significant reduction in the areal density of large islands and characteristically smoother films was achieved using a low deposition rate.
基金supported by National Natural Science Foundation of China(No.10747153)
文摘Based on the electromagnetic theory and by using an analytical technique-the transfer matrix method, the obliquely incident electromagnetic waves propagating in one-dimension plasma photonic crystals is studied. The dispersion relations for both the P-polarization waves and S-polarization waves, depending on the plasma density, plasma thickness and period, are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.51702245)the Fundamental Research Funds for the Central Universities(Grant No.WUT2021III065JC)
文摘Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated phototransistor based on the vertical HfSe_(2)/MoS_(2)heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse.Under bias,the phototransistor exhibits high responsivity of up to 1.42×103A/W,and ultrahigh specific detectivity of up to 1.39×1015cm·Hz^(1/2)·W^(-1).Moreover,it can also operate under zero bias with remarkable responsivity of 10.2 A/W,relatively high specific detectivity of 1.43×1014cm·Hz^(1/2)·W^(-1),ultralow dark current of 1.22 f A,and high on/off ratio of above 105.These results should be attributed to the fact that the vertical HfSe_(2)/MoS_(2)heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity.Therefore,the heterostructure provides a promising candidate for next generation high performance phototransistors.
基金Project supported by the National Natural Science Foundation of China(Nos.61176100,61274112)
文摘GaAs metal–oxide–semiconductor（MOS） capacitors with HfTiO as the gate dielectric and Al2O3 or ZnO as the interface passivation layer（IPL） are fabricated. X-ray photoelectron spectroscopy reveals that the Al2O3 IPL is more effective in suppressing the formation of native oxides and As diffusion than the ZnO IPL. Consequently, experimental results show that the device with Al2O3 IPL exhibits better interfacial and electrical properties than the device with ZnO IPL： lower interface-state density（7.2×10^12 eV1cm^2/, lower leakage current density（3.60×10^7A/cm^2 at Vg D1 V） and good C–V behavior.
基金Project supported by the Fundamental Research Funds for the Central Universities (Grant Nos. 2011-Ia-002 and 2012-Ia-031)
文摘Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect band gap. In this paper, we investigate the suitability of surface plasmon resonance Ag nanoparticles for enhancing optical absorption in the thin film solar cell. For evaluating the transmittance capability of Ag nanoparticles and the conventional antireflection film, an enhanced transmittance factor is introduced. We find that under the solar spectrum AM1.5, the transmittance of Ag nanoparticles with radius over 160 nm is equivalent to that of conventional textured antireflection film, and its effect is better than that of the planar antireflection film. The influence of the surrounding medium is also discussed.
文摘In this study we consider the boundary estimation of annular two-phase flow in a pipe with the potential distribution on the electrodes mounted on the outer boundary of the pipe, by taking use of electrical impedance tomography (EIT) technique with the numerical solution obtained from an improved boundary distributed source (IBDS) method. The particle swarm optimization (PSO) is used to iteratively seek the boundary configuration. The simulation results showed that PSO and EIT technique with numerical solution obtained from IBDS has been successfully applied to the monitoring of an annular two-phase flow.
基金support from CAS-CSIRO Joint Project(112111KYSB20210017)Natural Science Foundation of China(Nos.52361145847,52172260,52227803,U24A6003,52203368,52222212)the National Key R&D Program of China(2021YFB3800103).
文摘CsPbI_(3)perovskites with suitable bandgaps∼1.70 eV present distinct advantages for top-cell photovoltaic materials in tandem solar cells,however,relevant work has been rarely reported.This work designed a sandwich-like MoO_(X)/Ag/MoO_(X)(MAM)buffer layer as the front cell window layer to maximize incident light utilization efficiency for semi-transparent CsPbI_(3)solar cells and four terminal(4-T)stacked cells.Further investigation revealed that the MAM has to experience in-situ reaction between Ag metal and fresh MoO_(X),which can simultaneously ensure the transparency of the buffer layer and improve the carrier transportation and collection,except for protecting the underlying spiro-OMeTAD layer from the bombardment of magnetron sputtering.Thanks to this MAM buffer layer and a tunnel oxide passivating contact(TOPCon)bottom cell with edge passivation,semi-transparent CsPbI_(3)devices(aperture area:0.50 cm^(2))demonstrated a power conversion efficiency(PCE)of 18.86%while corresponding 4-T CsPbI_(3)/TOPCon tandem solar cells(PSTSCs)presented the PCE of 26.55%.Besides,we also fabricated semi-transparent CsPbI_(3)minimodules with 16.67%PCE and 4-T PSTSCs with 26.41%PCE(aperture area:6.62 cm^(2)).This work provided a new scalable strategy for transparent buffer layers by constructing in-situ generated sandwich structured buffer layer,which is suitable for perovskite tandem solar cells.
基金This work was supported by the National Basic Research Program of China （No. 2011CB933300）, the National Natural Science Foundation of China （Nos. 51671148, 51271134, J1210061, 11674251, 51501132, and 51601132）, the Hubei Provincial Natural Science Foundation of China （Nos. 2016CFB446 and 2016CFB155）, the Fundamental Research Funds for the Central Universities, and the CERS-1-26 （CERS-China Equip- ment and Education Resources System）, and the China Postdoctoral Science Foundation （No. 2014T70734）, and the Open Research Fund of Science and Technology on High Strength Structural Materials Laboratory （Central South University） and the Suzhou Science and Technology project （No. SYG201619）.
文摘Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidation stage is dominated by the dislocation-mediated oxidation behavior of Cu2O NCs via solid-solid transformations, leading to the formation of a new intermediate CuOx phase. The possible crystal structure of the CuOx phase is discussed. （2） Subsequently, CuOx is transformed into CuO by layer-by-layer oxidation. These results will help in understanding the oxidation mechanisms of copper oxides and pave the way for improving their structural diversity and exploiting their potential industrial applications.
