Background Bovine mastitis is one of the main causes of reduced production in dairy cows.The infection of the mammary gland is mainly caused by the bacterium Staphylococcus aureus,whose resistant strains make the trea...Background Bovine mastitis is one of the main causes of reduced production in dairy cows.The infection of the mammary gland is mainly caused by the bacterium Staphylococcus aureus,whose resistant strains make the treatment of mastitis with conventional antibiotics very difficult and result in high losses.Therefore,it is impor-tant to develop novel therapeutic agents to overcome the resistance of mastitis-causing strains.In this study,novel selenium-tellurium based nanoparticles(SeTeNPs)were synthesized and characterized.Their antibacterial activity and biocompatibility were evaluated both in vitro and in vivo using a bovine model.A total of 10 heifers were divided into experimental and control groups(5 animals each).After intramammary infection with methicillin resistant S.aureus(MRSA)and the development of clinical signs of mastitis,a dose of SeTeNPs was administered to all quarters in the experimental group.Results Based on in vitro tests,the concentration of 149.70 mg/L and 263.95 mg/L of Se and Te,respectively,was used for application into the mammary gland.Three days after SeTeNPs administration,MRSA counts in the experimental group showed a significant reduction(P<0.01)compared to the control group.The inhibitory effect observed within the in vitro experiments was thus confirmed,resulting in the suppression of infection in ani-mals.Moreover,the superior biocompatibility of SeTeNPs in the organism was demonstrated,as the nanoparticles did not significantly alter the inflammatory response or histopathology at the site of application,i.e.,mammary gland,compared to the control group(P>0.05).Additionally,the metabolic profile of the blood plasma as well as the histology of the main organs remained unaffected,indicating that the nanoparticles had no adverse effects on the organism.Conclusions Our findings suggest that SeTeNPs can be used as a promising treatment for bovine mastitis in the pres-ence of resistant bacteria.However,the current study is limited by its small sample size,making it primarily a proof of the concept for the efficacy of intramammary-applied SeTeNPs.Therefore,further research with a larger sample size is needed to validate these results.展开更多
Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited HfO2 dielectric and TaN electrodes are investigated for rf integrated circuit applications. For 12nm HfO2, the fabricated capacitor exhibits a high ...Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited HfO2 dielectric and TaN electrodes are investigated for rf integrated circuit applications. For 12nm HfO2, the fabricated capacitor exhibits a high capacitance density of 15.5fF/μm2 at 100kHz, a small leakage current density of 6.4 × 10^-9 A/cm^2 at 1.8V and 125℃, a breakdown electric field of 2.6 MV//cm as well as voltage coefficients of capacitance （VCCs） of 2110ppm/V^2 and -824 ppm/V at 100kHz. Further, it is deduced that the conduction mechanism in the high field range is dominated by the Poole-Frenkel emission, and the conduction mechanism in the low field range is possibly related to trap-assisted tunnelling. Finally, comparison of various HfO2 MIM capacitors is present, suggesting that the present MIM capacitor is a promising candidate for future rf integrated circuit application.展开更多
To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lif...To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lift-off process.This circuit consists of a single-fluxquantum(SFQ) pulse generator,a Josephson transmission line(JTL) and a T-flip flop(TFF),and it acts as a frequency divider.The values of the inductors in this circuit were extracted using InductEX and the basic function of this circuit was confirmed using the simulation software WRspice before fabrication.After fabrication,the basic parameters of this circuit were measured at ~2.5 K in a Janis He-3 cryostat.This work laid the theoretical and experimental basis for the future research on the RSFQqubit control circuits.展开更多
OBJECTIVE: To investigate a quantitative method for using radial artery pulse waveforms to assess the effect of pulsatile flow during cardiopulmonary bypass(CPB).METHODS: A total of 34 adults with heart disease who un...OBJECTIVE: To investigate a quantitative method for using radial artery pulse waveforms to assess the effect of pulsatile flow during cardiopulmonary bypass(CPB).METHODS: A total of 34 adults with heart disease who underwent open-heart surgery between April2010 and January 2011 were randomized into a pulsatile perfusion group(n=17) and a non-pulsatile perfusion group(n=17). Radial arterial pulse waveforms of pulsatile and non-pulsatile perfusion patients were observed and compared before and during CPB.RESULTS: No pulse waveform could be detected at patients' radial artery in both groups when the aorta was cross-clamped. Pulse waveforms could be detected at pulsatile perfusion patients' radial artery, but could not be detected at non-pulsatile perfusion patients' radial artery during CPB. Additionally, patients' pulse waveforms during pulsatile perfusion were lower than those before the operation.CONCLUSION: Our findings indicate that radial artery sphygmogram can be used as a valid indicator to evaluate the effectiveness of pulsatile perfusion during CPB.展开更多
In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass subs...In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass substrate has good antireflection properties. Its surface reflectance can be reduced by - 50% compared with planar glass. The HP arrays can make the unabsorbed light return to the absorbing layer of solar cells, and the ratio of second absorption approximately equals 30%. Thus, the glass substrate with the hemisphere pit arrays （HP glass） can effectively reduce the total reflectivity of a solar celt from 20% to 13%. The lip glass can also prolong the optical path length. The numerical results show that the total optical path length of the thin film Si solar cell covered with the HP glass increases from 2ω to 409. These results are basically consistent with the experimental results.展开更多
A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of t...A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of the infrared radiation in the QWIP, effective component of the vector potential <| A z |> along the QWIP growth direction ( z axis) due to the optical diffraction grating was calculated. (2) From the wave transmissions and the occupations of the electronic states, it was discussed that the dark current in the QWIP is determined by the drift diffusion current of carriers thermally excited from the ground sublevel in the quantum well to extended states above the barrier. (3) The photocurrent was investigated by the optical transition (absorption coefficient between the ground state to excited states due to the nonzero <| A z |> ). (4) By studying the inter diffusion of the Al atoms across the GaAs?AlGaAs heterointerfaces,the mobility of the drift diffusion carriers in the excited states was calculated, so the measurement results of the dark current and photocurrent spectra can be explained theoretically. With the complete quantum mechanical descriptions of (1 4), QWIP device design and optimization are possible.展开更多
Ultra-thin Al2O3 dielectric films have been deposited on Si substrates by using trimethyl aluminium （TMA） and water as precursors in an atomic layer deposition （ALD） system. Growth of the interracial layer between...Ultra-thin Al2O3 dielectric films have been deposited on Si substrates by using trimethyl aluminium （TMA） and water as precursors in an atomic layer deposition （ALD） system. Growth of the interracial layer between ultra-thin Al2O3 and the Si substrate is effectively suppressed by a long-time TMA surface pretreatment of the Si substrate prior to A1203 atomic layer deposition. High resolution transmission electron microscopy （TEM） images show that the thickness of the interracial layer is reduced to be 0.5nm for the sample with TMA pretreatment lasting 3600s. The x-ray photoelectron spectroscopy results indicate that the A1203 film deposited on the TMApretreated Si surface exhibits very good thermal stability. However, a hysteresis of about 50mV is observed in the C- V curve of the samples with the TMA pretreatment.展开更多
Halo structure is added to sub-100 nm surrounding-gate metal-oxide-semiconductor fieldeffect-transistors （MOS- FETs） to suppress short channel effect. This paper develops the analytical surface potential and thresho...Halo structure is added to sub-100 nm surrounding-gate metal-oxide-semiconductor fieldeffect-transistors （MOS- FETs） to suppress short channel effect. This paper develops the analytical surface potential and threshold voltage models based on the solution of Poisson＇s equation in fully depleted condition for symmetric halo-doped cylindrical surrounding gate MOSFETs. The performance of the halo-doped device is studied and the validity of the analytical models is verified by comparing the analytical results with the simulated data by three dimensional numerical device simulator Davinci. It shows that the halo doping profile exhibits better performance in suppressing threshold voltage roll-off and drain-induced barrier lowering, and increasing carrier transport efficiency. The derived analytical models are in good agreement with Davinci.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
Organic–inorganic halide perovskite(OIHP)solar cells have garnered great attention in the last decade since they continuously approach the Shockley–Queisser Limit.Compared with conventional organic and inorganic sem...Organic–inorganic halide perovskite(OIHP)solar cells have garnered great attention in the last decade since they continuously approach the Shockley–Queisser Limit.Compared with conventional organic and inorganic semiconductors,OIHPs possess the high tolerance on defects due to the dominated intrinsically shallow-level carrier-trapping centers.However,the existence of defects still causes the ion migration,produces the hysteresis effect,and accelerates the film degradation,eventually suppressing the device efficiency and stability.In this Review Article,we summarize recent impressive advance on passivating OIHP defects and discuss the future horizon of exploiting high-efficiency and long-stability OIHP solar cells in terms of defect managements.展开更多
Superconducting transition edge sensor(TES)bolometers require superconducting films to have controllable transition temperatures T_(c)in different practical applications.The value of T_(c)strongly affects thermal cond...Superconducting transition edge sensor(TES)bolometers require superconducting films to have controllable transition temperatures T_(c)in different practical applications.The value of T_(c)strongly affects thermal conductivity and thermal noise performance of TES detectors.Al films doped with Mn(Al-Mn)of different concentrations can accomplish tunable T_(c)A magnetron sputtering machine is used to deposit the Al-Mn films in this study.Fabrication parameters including sputtering pressure and annealing process are studied and their influences on T_(c)and superconducting transition widthΔT_(c)are optimized.The Al-Mn films withΔT_(c)below 1.0 mK for T_(c)in a range of 520 mK-580 mK are successfully fabricated.展开更多
Fluorescein/polyvinyl pyrrolidone （PVP） composite nanofibers with different fluorescein loadings （with a weight concentration of 0-5.0%） are fabricated via electrospinning. Morphologies, structures and photolumine...Fluorescein/polyvinyl pyrrolidone （PVP） composite nanofibers with different fluorescein loadings （with a weight concentration of 0-5.0%） are fabricated via electrospinning. Morphologies, structures and photoluminescent （PL） prop- erties of these straight, helical or wavelike fibers are characterized by scanning electron microscopy （SEM）, fluorescence microscopy and a spectrophotometer. It is found that the maximum emission of the as-spun fluorescein/PVP fibers occurs at 510 nm. The PL intensity of the composite fiber increases with fluorescein concentration, then fluorescence quenching appears when the concentration reaches 1.67%. The mechanism of fluorescence quenching of fiuorescein is discussed. In addition, the composite fibers exhibit a much stronger PL intensity than fluorescein/PVP bulk film owing to larger specific surface area, which makes them promising materials for biomedical applications such as probes and sensors.展开更多
This paper concerns the optimization problem for multilayered ultrasonic transducer with active porous piezoelectric layer. The dependences of the effective moduli for porous piezoelectric material on porosity have be...This paper concerns the optimization problem for multilayered ultrasonic transducer with active porous piezoelectric layer. The dependences of the effective moduli for porous piezoelectric material on porosity have been previously obtained and allowed to decrease the number of design variables. The multiobjective optimization problem based on the Pareto-frontier calculation has been solved using the live-link of finite-element (FE) package Comsol Multiphysics with MATLAB.展开更多
A novel operation mechanism of capacitorless SOl-DRAM （silicon on insulator dynamic random access memory） cell using impact ionization and GIDL （gated-induce drain leakage） effects for write ＂1＂ operation was pr...A novel operation mechanism of capacitorless SOl-DRAM （silicon on insulator dynamic random access memory） cell using impact ionization and GIDL （gated-induce drain leakage） effects for write ＂1＂ operation was proposed. The conventional capacitorless DRAM cell with single charge generating effect is either high speed or low power, while the proposed DG-FinFET （double-gate fin field effect transistor） cell employs the efficient integration of impact ionization and GIDL effects by coupling the front and back gates with optimal body doping profile and proper bias conditions, yielding high speed low power performance. The simulation results demonstrate ideal characteristics in both cell operations and power consumption. Low power consumption is achieved by using GIDL current at 0. luA when the coupling between the front and back gates restrains the impact ionization current in the first phase. The write operation of the cell is within Ins attributed to significant current of the impact ionization effect in the second phase. By shortening second phase, power consumption could be further decreased. The ratio of read ＂1＂ and read ＂0＂ current is more than 9.38E5. Moreover, the cell has great retention characteristics.展开更多
Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction （XRD）, high-...Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction （XRD）, high- resolution transmission electron microscopy （HRTEM）, and x-ray photoelectron spectroscopy （XPS）. The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3 nm and 0.Snm, respectively. XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.展开更多
We investigate the molecular-beam-epitaxy growth of highly relaxed Si0.45 Ge0.55 films with very low dislocation densities. By using the Si3N4 film as the mask material, the Si0.45Ge0.55 film can be grown on a composi...We investigate the molecular-beam-epitaxy growth of highly relaxed Si0.45 Ge0.55 films with very low dislocation densities. By using the Si3N4 film as the mask material, the Si0.45Ge0.55 film can be grown on a compositionally stepwise graded SiGe buffer layer in 3 μm× 3 μm windows on a Si （001） substrate. Raman scattering spectroscopy measurement shows that more than 90% strain of the Si0.45Ge0.55 film is relaxed, and almost neither misfit dislocation lines nor etch pits of thread dislocations could be observed when the sample is etched by the modified Schimmel etchant. We suggest that the results can be explained by influence of the edge-induced strain relaxation of the epitaxial film and the edge-induced stress of the mask material.展开更多
The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a depos...The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330℃. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar^＋ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.展开更多
A Ⅲ-Ⅴ heterojunction tunneling field-effect transistor(TFET) can enhance the on-state current effectively,and GaAsSb/InGaAs heterojunction exhibits better performance with the adjustable band alignment by modulating...A Ⅲ-Ⅴ heterojunction tunneling field-effect transistor(TFET) can enhance the on-state current effectively,and GaAsSb/InGaAs heterojunction exhibits better performance with the adjustable band alignment by modulating the alloy composition.In this paper,the performance of the cylindrical surrounding-gate GaAsSb/InGaAs heterojunction TFET with gate-drain underlap is investigated by numerical simulation.We validate that reducing drain doping concentration and increasing gate-drain underlap could be effective ways to reduce the off-state current and subthreshold swing(SS),while increasing source doping concentration and adjusting the composition of GaAsSbInGaAs can improve the on-state current.In addition,the resonant TFET based on GaAsSb/InGaAs is also studied,and the result shows that the minimum and average of SS reach 11 mV/decade and 20 mV/decade for five decades of drain current,respectively,and is much superior to the conventional TFET.展开更多
Field emission properties of zinc oxide （ZnO） nanoparticles （NPs） decorated carbon nanotubes （CNTs） are investigated experimentally and theoretically. CNTs are in situ decorated with ZnO NPs during the growth pr...Field emission properties of zinc oxide （ZnO） nanoparticles （NPs） decorated carbon nanotubes （CNTs） are investigated experimentally and theoretically. CNTs are in situ decorated with ZnO NPs during the growth process by chemical vapor deposition using a carbon source from the iron phthalocyanine pyrolysis. The experimental field emission test shows that the ZnO NP decoration significantly improves the emission current from 50 μA to 275 μA at 550 V and the reduced threshold voltage from 450 V to 350 V. The field emission mechanism of ZnO NPs on CNTs is theoretically studied by the density functional theory （DFT） combined with the Penn-Plummer method. The ZnO NPs reconstruct the ZnO-CNT structure and pull down the surface barrier of the entire emitter system to 0.49 eV so as to reduce the threshold electric field. The simulation results suggest that the presence of ZnO NPs would increase the LDOS near the Fermi level and increase the emission current. The calculation results are consistent with the experiment results.展开更多
This paper investigates the thermal activation behaviour of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height by numerical simulation. The analytical Gaussian distribution model...This paper investigates the thermal activation behaviour of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height by numerical simulation. The analytical Gaussian distribution model predicted that the I-VT curves may intersect with the possibility of the negative thermal activation of current, but may be contradictory to the thermionic emission mechanism in a Schottky diode. It shows that the cause of the unphysical phenomenon is related to the incorrect calculation of current across very low barriers. It proposes that junction voltage Vj, excluding the voltage drop across series resistance from the external bias, is a crucial parameter for correct calculation of the current across very low barriers. For correctly employing the thermionic emission model, Vj needs to be smaller than the barrier height Ф. With proper scheme of series resistance connection where the condition of Vj 〉 Ф is guaranteed, I-V T curves of an inhomogeneous Schottky diode with a Gaussian distribution of barrier height have been simulated, which demonstrate normal thermal activation. Although the calculated results exclude the intersecting possibility of I-V T curves with an assumption of temperature-independent series resistance, it shows that the intersecting is possible when the series resistance has a positive temperature coefficient. Finally, the comparison of our numerical and analytical results indicates that the analytical Gaussian distribution model is valid and accurate in analysing I-V-T curves only for small barrier height inhomogeneity.展开更多
基金Financial support from ERDF “Multidisciplinary research to increase application potential of nanomaterials in agricultural practice” (No.CZ.02.1.01/0.0/0.0/16_025/0007314)the assistance provided by the Research Infrastructure Nano Envi Cz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LM2018124+4 种基金Czech Nano Lab Research Infrastructure supported by MEYS CR (LM2023051)Grant Agency of Gregor Johann Mendel (C-MNG-23–002)further supported by the Ministry of Agriculture of the Czech Republic by Grant RO0523Internal Grant Agency of University of Veterinary Sciences Brno (223/2024/FVHE)the National Institute of Virology and Bacteriology project (Programme EXCELES, Project ID No. LX22NPO5103)-Funded by the European Union-Next Generation EU.
文摘Background Bovine mastitis is one of the main causes of reduced production in dairy cows.The infection of the mammary gland is mainly caused by the bacterium Staphylococcus aureus,whose resistant strains make the treatment of mastitis with conventional antibiotics very difficult and result in high losses.Therefore,it is impor-tant to develop novel therapeutic agents to overcome the resistance of mastitis-causing strains.In this study,novel selenium-tellurium based nanoparticles(SeTeNPs)were synthesized and characterized.Their antibacterial activity and biocompatibility were evaluated both in vitro and in vivo using a bovine model.A total of 10 heifers were divided into experimental and control groups(5 animals each).After intramammary infection with methicillin resistant S.aureus(MRSA)and the development of clinical signs of mastitis,a dose of SeTeNPs was administered to all quarters in the experimental group.Results Based on in vitro tests,the concentration of 149.70 mg/L and 263.95 mg/L of Se and Te,respectively,was used for application into the mammary gland.Three days after SeTeNPs administration,MRSA counts in the experimental group showed a significant reduction(P<0.01)compared to the control group.The inhibitory effect observed within the in vitro experiments was thus confirmed,resulting in the suppression of infection in ani-mals.Moreover,the superior biocompatibility of SeTeNPs in the organism was demonstrated,as the nanoparticles did not significantly alter the inflammatory response or histopathology at the site of application,i.e.,mammary gland,compared to the control group(P>0.05).Additionally,the metabolic profile of the blood plasma as well as the histology of the main organs remained unaffected,indicating that the nanoparticles had no adverse effects on the organism.Conclusions Our findings suggest that SeTeNPs can be used as a promising treatment for bovine mastitis in the pres-ence of resistant bacteria.However,the current study is limited by its small sample size,making it primarily a proof of the concept for the efficacy of intramammary-applied SeTeNPs.Therefore,further research with a larger sample size is needed to validate these results.
基金Supported by the National Natural Science Foundation of China under Grant No 90607023, the Shanghai Pujiang Programme under Grant No 05PJ14017, and the SRF for R0CS, SEM, and the Micro/Nano-electronics Science and Technology Innovation Platform （985）, and the Ministry of Education of China in the International Research Training Group （Materials and Concepts for Advanced Interconnects）.
文摘Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited HfO2 dielectric and TaN electrodes are investigated for rf integrated circuit applications. For 12nm HfO2, the fabricated capacitor exhibits a high capacitance density of 15.5fF/μm2 at 100kHz, a small leakage current density of 6.4 × 10^-9 A/cm^2 at 1.8V and 125℃, a breakdown electric field of 2.6 MV//cm as well as voltage coefficients of capacitance （VCCs） of 2110ppm/V^2 and -824 ppm/V at 100kHz. Further, it is deduced that the conduction mechanism in the high field range is dominated by the Poole-Frenkel emission, and the conduction mechanism in the low field range is possibly related to trap-assisted tunnelling. Finally, comparison of various HfO2 MIM capacitors is present, suggesting that the present MIM capacitor is a promising candidate for future rf integrated circuit application.
基金financially supported by the Natural Science Foundation of China (No.60836001)the State Key Program for Basic Research of China (No.2011CBA00304)the Tsinghua University Initiative Scientific Research Program (No. 20131089314)
文摘To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lift-off process.This circuit consists of a single-fluxquantum(SFQ) pulse generator,a Josephson transmission line(JTL) and a T-flip flop(TFF),and it acts as a frequency divider.The values of the inductors in this circuit were extracted using InductEX and the basic function of this circuit was confirmed using the simulation software WRspice before fabrication.After fabrication,the basic parameters of this circuit were measured at ~2.5 K in a Janis He-3 cryostat.This work laid the theoretical and experimental basis for the future research on the RSFQqubit control circuits.
基金Grants from the National Natural Science Foundation of China(No.81173200,No.81373556)the Research and Assessment of the Effects of Pulsatile Perfusion During Cardiopulmonary Bypass Based on the Monitoring"Cunkou"Pulse Waveforms of Traditional Chinese Medicine Research Fund of Shanghai Municipal Public Health Bureau(No.2010J015A)
文摘OBJECTIVE: To investigate a quantitative method for using radial artery pulse waveforms to assess the effect of pulsatile flow during cardiopulmonary bypass(CPB).METHODS: A total of 34 adults with heart disease who underwent open-heart surgery between April2010 and January 2011 were randomized into a pulsatile perfusion group(n=17) and a non-pulsatile perfusion group(n=17). Radial arterial pulse waveforms of pulsatile and non-pulsatile perfusion patients were observed and compared before and during CPB.RESULTS: No pulse waveform could be detected at patients' radial artery in both groups when the aorta was cross-clamped. Pulse waveforms could be detected at pulsatile perfusion patients' radial artery, but could not be detected at non-pulsatile perfusion patients' radial artery during CPB. Additionally, patients' pulse waveforms during pulsatile perfusion were lower than those before the operation.CONCLUSION: Our findings indicate that radial artery sphygmogram can be used as a valid indicator to evaluate the effectiveness of pulsatile perfusion during CPB.
基金Project supported by the National High-Tech Research and Development Program of China(Grant No.2011AA050518)
文摘In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass substrate has good antireflection properties. Its surface reflectance can be reduced by - 50% compared with planar glass. The HP arrays can make the unabsorbed light return to the absorbing layer of solar cells, and the ratio of second absorption approximately equals 30%. Thus, the glass substrate with the hemisphere pit arrays （HP glass） can effectively reduce the total reflectivity of a solar celt from 20% to 13%. The lip glass can also prolong the optical path length. The numerical results show that the total optical path length of the thin film Si solar cell covered with the HP glass increases from 2ω to 409. These results are basically consistent with the experimental results.
文摘A complete quantum mechanical model for GaAs?AlGaAs quantum well infrared photodetectors(QWIPs) is presented here. The model consisted of four parts: (1) Starting with the description of the electromagnetic field of the infrared radiation in the QWIP, effective component of the vector potential <| A z |> along the QWIP growth direction ( z axis) due to the optical diffraction grating was calculated. (2) From the wave transmissions and the occupations of the electronic states, it was discussed that the dark current in the QWIP is determined by the drift diffusion current of carriers thermally excited from the ground sublevel in the quantum well to extended states above the barrier. (3) The photocurrent was investigated by the optical transition (absorption coefficient between the ground state to excited states due to the nonzero <| A z |> ). (4) By studying the inter diffusion of the Al atoms across the GaAs?AlGaAs heterointerfaces,the mobility of the drift diffusion carriers in the excited states was calculated, so the measurement results of the dark current and photocurrent spectra can be explained theoretically. With the complete quantum mechanical descriptions of (1 4), QWIP device design and optimization are possible.
文摘Ultra-thin Al2O3 dielectric films have been deposited on Si substrates by using trimethyl aluminium （TMA） and water as precursors in an atomic layer deposition （ALD） system. Growth of the interracial layer between ultra-thin Al2O3 and the Si substrate is effectively suppressed by a long-time TMA surface pretreatment of the Si substrate prior to A1203 atomic layer deposition. High resolution transmission electron microscopy （TEM） images show that the thickness of the interracial layer is reduced to be 0.5nm for the sample with TMA pretreatment lasting 3600s. The x-ray photoelectron spectroscopy results indicate that the A1203 film deposited on the TMApretreated Si surface exhibits very good thermal stability. However, a hysteresis of about 50mV is observed in the C- V curve of the samples with the TMA pretreatment.
基金Project supported by the National Natural Science Foundation of China (Grant No 10771168)the State Key Development Program for Basic Research of China (Grant No 2005CB321701)Shaanxi Natural Science Foundation Program of China(Grant No SJ08-ZT13)
文摘Halo structure is added to sub-100 nm surrounding-gate metal-oxide-semiconductor fieldeffect-transistors （MOS- FETs） to suppress short channel effect. This paper develops the analytical surface potential and threshold voltage models based on the solution of Poisson＇s equation in fully depleted condition for symmetric halo-doped cylindrical surrounding gate MOSFETs. The performance of the halo-doped device is studied and the validity of the analytical models is verified by comparing the analytical results with the simulated data by three dimensional numerical device simulator Davinci. It shows that the halo doping profile exhibits better performance in suppressing threshold voltage roll-off and drain-induced barrier lowering, and increasing carrier transport efficiency. The derived analytical models are in good agreement with Davinci.
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Organic–inorganic halide perovskite(OIHP)solar cells have garnered great attention in the last decade since they continuously approach the Shockley–Queisser Limit.Compared with conventional organic and inorganic semiconductors,OIHPs possess the high tolerance on defects due to the dominated intrinsically shallow-level carrier-trapping centers.However,the existence of defects still causes the ion migration,produces the hysteresis effect,and accelerates the film degradation,eventually suppressing the device efficiency and stability.In this Review Article,we summarize recent impressive advance on passivating OIHP defects and discuss the future horizon of exploiting high-efficiency and long-stability OIHP solar cells in terms of defect managements.
基金the National Natural Science Foundation of China(Grant Nos.11653001 and 11653004)。
文摘Superconducting transition edge sensor(TES)bolometers require superconducting films to have controllable transition temperatures T_(c)in different practical applications.The value of T_(c)strongly affects thermal conductivity and thermal noise performance of TES detectors.Al films doped with Mn(Al-Mn)of different concentrations can accomplish tunable T_(c)A magnetron sputtering machine is used to deposit the Al-Mn films in this study.Fabrication parameters including sputtering pressure and annealing process are studied and their influences on T_(c)and superconducting transition widthΔT_(c)are optimized.The Al-Mn films withΔT_(c)below 1.0 mK for T_(c)in a range of 520 mK-580 mK are successfully fabricated.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11074138,11004114,60906054, and50825206)the Shandong Provincial Natural Science Foundation for Distinguished Young Scholars,China (Grant No. JQ201103)+2 种基金the Taishan Scholars Program of Shandong Province, Chinathe National Basic Research Program of China (Grant No. 2012CB722705)the National High Technology Research and Development Program of China (Grant No. 2011AA100706)
文摘Fluorescein/polyvinyl pyrrolidone （PVP） composite nanofibers with different fluorescein loadings （with a weight concentration of 0-5.0%） are fabricated via electrospinning. Morphologies, structures and photoluminescent （PL） prop- erties of these straight, helical or wavelike fibers are characterized by scanning electron microscopy （SEM）, fluorescence microscopy and a spectrophotometer. It is found that the maximum emission of the as-spun fluorescein/PVP fibers occurs at 510 nm. The PL intensity of the composite fiber increases with fluorescein concentration, then fluorescence quenching appears when the concentration reaches 1.67%. The mechanism of fluorescence quenching of fiuorescein is discussed. In addition, the composite fibers exhibit a much stronger PL intensity than fluorescein/PVP bulk film owing to larger specific surface area, which makes them promising materials for biomedical applications such as probes and sensors.
文摘This paper concerns the optimization problem for multilayered ultrasonic transducer with active porous piezoelectric layer. The dependences of the effective moduli for porous piezoelectric material on porosity have been previously obtained and allowed to decrease the number of design variables. The multiobjective optimization problem based on the Pareto-frontier calculation has been solved using the live-link of finite-element (FE) package Comsol Multiphysics with MATLAB.
文摘A novel operation mechanism of capacitorless SOl-DRAM （silicon on insulator dynamic random access memory） cell using impact ionization and GIDL （gated-induce drain leakage） effects for write ＂1＂ operation was proposed. The conventional capacitorless DRAM cell with single charge generating effect is either high speed or low power, while the proposed DG-FinFET （double-gate fin field effect transistor） cell employs the efficient integration of impact ionization and GIDL effects by coupling the front and back gates with optimal body doping profile and proper bias conditions, yielding high speed low power performance. The simulation results demonstrate ideal characteristics in both cell operations and power consumption. Low power consumption is achieved by using GIDL current at 0. luA when the coupling between the front and back gates restrains the impact ionization current in the first phase. The write operation of the cell is within Ins attributed to significant current of the impact ionization effect in the second phase. By shortening second phase, power consumption could be further decreased. The ratio of read ＂1＂ and read ＂0＂ current is more than 9.38E5. Moreover, the cell has great retention characteristics.
文摘Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction （XRD）, high- resolution transmission electron microscopy （HRTEM）, and x-ray photoelectron spectroscopy （XPS）. The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3 nm and 0.Snm, respectively. XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.
基金Supported by the National Natural Science Foundation of China under Grant No 60376012, and the State Key Laboratory of Functional Materials of Informatics, Chinese Academy of Sciences.
文摘We investigate the molecular-beam-epitaxy growth of highly relaxed Si0.45 Ge0.55 films with very low dislocation densities. By using the Si3N4 film as the mask material, the Si0.45Ge0.55 film can be grown on a compositionally stepwise graded SiGe buffer layer in 3 μm× 3 μm windows on a Si （001） substrate. Raman scattering spectroscopy measurement shows that more than 90% strain of the Si0.45Ge0.55 film is relaxed, and almost neither misfit dislocation lines nor etch pits of thread dislocations could be observed when the sample is etched by the modified Schimmel etchant. We suggest that the results can be explained by influence of the edge-induced strain relaxation of the epitaxial film and the edge-induced stress of the mask material.
基金Supported by the National Natural Science Foundation in China under Grant No 60476010, the Science and Technology Committee of the Shanghai Municipality （04QMX1407）, the National Basic Research Programme of China under Grant No 2006CB302703, and the International Research Training Group （Materials and Concepts for Advanced Interconnects）.
文摘The polycrystalline ruthenium films are grown on TaN substrates by atomic layer deposition （ALD） using bis（cyclopentadienyl） ruthenium [RuCp2] and oxygen as ruthenium precursor and reactant respectively at a deposition temperature of 330℃. The low-energy Ar ion bombardment and Ru pre-deposition are performed to the underlying TaN substrates before ALD process in order to improve the Ru nucleation. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy are carried out to characterize the properties of ALD Ru films. The results show that the nucleation density of Ru films with Ar^＋ bombardment to the underlying TaN substrates is much higher than that of the ones without any pretreatment. The possible reasons are discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176038 and 61474093)the Science and Technology Planning Project of Guangdong Province,China(Grant No.2015A010103002)the Technology Development Program of Shaanxi Province,China(Grant No.2016GY-075)
文摘A Ⅲ-Ⅴ heterojunction tunneling field-effect transistor(TFET) can enhance the on-state current effectively,and GaAsSb/InGaAs heterojunction exhibits better performance with the adjustable band alignment by modulating the alloy composition.In this paper,the performance of the cylindrical surrounding-gate GaAsSb/InGaAs heterojunction TFET with gate-drain underlap is investigated by numerical simulation.We validate that reducing drain doping concentration and increasing gate-drain underlap could be effective ways to reduce the off-state current and subthreshold swing(SS),while increasing source doping concentration and adjusting the composition of GaAsSbInGaAs can improve the on-state current.In addition,the resonant TFET based on GaAsSb/InGaAs is also studied,and the result shows that the minimum and average of SS reach 11 mV/decade and 20 mV/decade for five decades of drain current,respectively,and is much superior to the conventional TFET.
基金supported by the National Natural Science Foundation of China(Grant Nos.91123018,61172040,and 61172041)the Natural Science Foundation of Shaanxi Province,China(Grant No.2014JM7277)
文摘Field emission properties of zinc oxide （ZnO） nanoparticles （NPs） decorated carbon nanotubes （CNTs） are investigated experimentally and theoretically. CNTs are in situ decorated with ZnO NPs during the growth process by chemical vapor deposition using a carbon source from the iron phthalocyanine pyrolysis. The experimental field emission test shows that the ZnO NP decoration significantly improves the emission current from 50 μA to 275 μA at 550 V and the reduced threshold voltage from 450 V to 350 V. The field emission mechanism of ZnO NPs on CNTs is theoretically studied by the density functional theory （DFT） combined with the Penn-Plummer method. The ZnO NPs reconstruct the ZnO-CNT structure and pull down the surface barrier of the entire emitter system to 0.49 eV so as to reduce the threshold electric field. The simulation results suggest that the presence of ZnO NPs would increase the LDOS near the Fermi level and increase the emission current. The calculation results are consistent with the experiment results.
基金supported by Shanghai-Applied Materials Research and Development Fund (Grant Nos.07SA06 and 09700714200)Fok Ying Tong Education Foundation (Grant No.114006)
文摘This paper investigates the thermal activation behaviour of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height by numerical simulation. The analytical Gaussian distribution model predicted that the I-VT curves may intersect with the possibility of the negative thermal activation of current, but may be contradictory to the thermionic emission mechanism in a Schottky diode. It shows that the cause of the unphysical phenomenon is related to the incorrect calculation of current across very low barriers. It proposes that junction voltage Vj, excluding the voltage drop across series resistance from the external bias, is a crucial parameter for correct calculation of the current across very low barriers. For correctly employing the thermionic emission model, Vj needs to be smaller than the barrier height Ф. With proper scheme of series resistance connection where the condition of Vj 〉 Ф is guaranteed, I-V T curves of an inhomogeneous Schottky diode with a Gaussian distribution of barrier height have been simulated, which demonstrate normal thermal activation. Although the calculated results exclude the intersecting possibility of I-V T curves with an assumption of temperature-independent series resistance, it shows that the intersecting is possible when the series resistance has a positive temperature coefficient. Finally, the comparison of our numerical and analytical results indicates that the analytical Gaussian distribution model is valid and accurate in analysing I-V-T curves only for small barrier height inhomogeneity.
