Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a no...Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a novel approach to accomplish this task at room temperature by resistive switching(RS) via electrochemical metallization(ECM) in a device with the stack of Si/SiO_(2)/Ta/Pt/Ag/Mn-doped ZnO(MZO)/Pt/Co/Pt/ITO.By applying certain voltages,the device could be set at high-resistance-state(HRS) and low-resistance-state(LRS),accompanied with a larger and a smaller coercivity(H_(C)),respectively,which demonstrates a nonvolatile E-field control of PMA.Based on our previous studies and the present control experiments,the electric modulation of PMA can be briefly explained as follows.At LRS,the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich,leading to weakening of PMA and reduction of H_(C).In contrast,at HRS,most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich,causing partial recovery of PMA and an increase of H_(C).This work provides a new clue to designing low-power spintronic devices based on PMA films.展开更多
A metal foil spark gap switch is fabricated by using magnetron sputtering deposition technology and standard microelectronic technology. The switch has two main electrodes and a trigger electrode. Stylus profiler is e...A metal foil spark gap switch is fabricated by using magnetron sputtering deposition technology and standard microelectronic technology. The switch has two main electrodes and a trigger electrode. Stylus profiler is employed to measure the distance between the main electrodes and the dimensions of the trigger electrode. The discharge characteristics of the metal foil spark gap switch are discussed. The switch has short delay time and low time jitter. When it is fired by a conventional capacitive discharge unit (CDU), the firing circuit has low inductance and resistance. Because of its low profile structure, it can be easily integrated with the bridge foil used in a conventional exploding foil initiator system (EFIS).展开更多
In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the p...In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the polarity of forming voltage. The mechanisms of the URS and BRS behaviors could be attributed to the electric-field-induced migration of oxygen vacancies （Vo） and metal-Ag conducting filaments （CFs） respectively, which are confirmed by investigating the temperature dependences of low resistance states in both modes. Furthermore, we compare the resistive switching （RS） characteristics （e.g., forming and switching voltages, reset current and resistance states） between these two modes based on Vo- and Ag-CFs. The BRS mode shows better switching uniformity and lower power than the URS mode. Both of these modes exhibit good RS performances, including good retention, reliable cycling and high-speed switching. The result indicates that the coexistence of URS and BRS behaviors in a single device has great potential applications in future nonvolatile multi-level memory.展开更多
Bipolar resistance switching characteristics are investigated in Cu/sputtered-HfO_2/Pt structure in the application of resistive random access memory（RRAM）.The conduction mechanism of the structure is characterized ...Bipolar resistance switching characteristics are investigated in Cu/sputtered-HfO_2/Pt structure in the application of resistive random access memory（RRAM）.The conduction mechanism of the structure is characterized to be SCLC conduction.The dependence of resistances in both high resistance state（HRS） and low resistance state（LRS） on the temperature and device area are studied.Then,the composition and chemical bonding state of Cu and Hf at Cu/HfO_2 interface region are analyzed by x-ray photoelectron spectroscopy（XPS）.Combining the electrical characteristics and the chemical structure at the interface,a model for the resistive switching effect in Cu/HfO_2/Pt stack is proposed.According to this model,the generation and recovery of oxygen vacancies in the HfO_2 film are responsible for the resistance change.展开更多
We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelen...We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.展开更多
Electric-field-induced resistance switching （RS） phenomena have been studied for over 60 years in metal/dielectrics/metal structures. In these experiments a wide range of dielectrics have been studied including bina...Electric-field-induced resistance switching （RS） phenomena have been studied for over 60 years in metal/dielectrics/metal structures. In these experiments a wide range of dielectrics have been studied including binary transition metal oxides, perovskite oxides, chalcogenides, carbon- and silicon-based materials, as well as organic materials. RS phenomena can be used to store information and offer an attractive performance, which encompasses fast switching speeds, high scalability, and the desirable compatibility with Si-based complementary metal-oxide-semiconductor fabrication. This is promising for nonvolatile memory technology, i.e., resistance random access memory （RRAM）. However, a comprehensive understanding of the underlying mechanism is still lacking. This impedes faster product development as well as accurate assessment of the device performance potential. Generally speaking, RS occurs not in the entire dielectric but only in a small, confined region, which results from the local variation of conductivity in dielectrics. In this review, we focus on the RS in oxides with such an inhomogeneous conductivity. According to the origin of the conductivity inhomogeneity, the RS phenomena and their working mechanism are reviewed by dividing them into two aspects： interface RS, based on the change of contact resistance at metal/oxide interface due to the change of Schottky barrier and interface chemical layer, and bulk RS, realized by the formation, connection, and disconnection of conductive channels in the oxides. Finally the current challenges of RS investigation and the potential improvement of the RS performance for the nonvolatile memories are discussed.展开更多
In this work, we investigated resistive switching behavior of CrO<sub>x</sub> thin films grown by using sputtering technique. Conventional I-V measurements obtained from Ag/CrO<sub>x</sub>/Pt/T...In this work, we investigated resistive switching behavior of CrO<sub>x</sub> thin films grown by using sputtering technique. Conventional I-V measurements obtained from Ag/CrO<sub>x</sub>/Pt/Ti/SiO<sub>2</sub>/Si structures depict the bipolar switching behavior, which is controlled by formation/dissolution processes of Ag conducting filaments through electrochemical redox reaction under external electric field driven. Conductive atomic force microscopy (C-AFM) technique provides the valuable mapping images of existing Ag filaments at low resistance state as well as the characteristics of filament distributions and diameters. This study also reveals that where the higher amplitude of topography is, the easier possibility of forming conducting filament paths is on CrO<sub>x</sub> surface films.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
It is important to consider the changing states in hedging.The Markov regime-switching dynamic correlation multivariate stochastic volatility( MRS-DC-MSV) model was proposed to solve this issue. DC-MSV model and MRS-D...It is important to consider the changing states in hedging.The Markov regime-switching dynamic correlation multivariate stochastic volatility( MRS-DC-MSV) model was proposed to solve this issue. DC-MSV model and MRS-DC-MSV model were used to calculate the time-varying hedging ratios and compare the hedging performance. The Markov chain Monte Carlo( MCMC) method was used to estimate the parameters. The results showed that,there were obviously two economic states in Chinese financial market. Two models all did well in hedging,but the performance of MRS-DCMSV model was better. It could reduce risk by nearly 90%. Thus,in the hedging period,changing states is a factor that cannot be neglected.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
基金Project supported by the National Key Research and Development Program of China (Grant No. 2022YFA1403602)the National Natural Science Foundation of China (Grant Nos. 51971109, 52025012, and 52001169)。
文摘Electric-field control of perpendicular magnetic anisotropy(PMA) is a feasible way to manipulate perpendicular magnetization,which is of great importance for realizing energy-efficient spintronics.Here,we propose a novel approach to accomplish this task at room temperature by resistive switching(RS) via electrochemical metallization(ECM) in a device with the stack of Si/SiO_(2)/Ta/Pt/Ag/Mn-doped ZnO(MZO)/Pt/Co/Pt/ITO.By applying certain voltages,the device could be set at high-resistance-state(HRS) and low-resistance-state(LRS),accompanied with a larger and a smaller coercivity(H_(C)),respectively,which demonstrates a nonvolatile E-field control of PMA.Based on our previous studies and the present control experiments,the electric modulation of PMA can be briefly explained as follows.At LRS,the Ag conductive filaments form and pass through the entire MZO layer and finally reach the Pt/Co/Pt sandwich,leading to weakening of PMA and reduction of H_(C).In contrast,at HRS,most of the Ag filaments dissolve and leave away from the Pt/Co/Pt sandwich,causing partial recovery of PMA and an increase of H_(C).This work provides a new clue to designing low-power spintronic devices based on PMA films.
文摘A metal foil spark gap switch is fabricated by using magnetron sputtering deposition technology and standard microelectronic technology. The switch has two main electrodes and a trigger electrode. Stylus profiler is employed to measure the distance between the main electrodes and the dimensions of the trigger electrode. The discharge characteristics of the metal foil spark gap switch are discussed. The switch has short delay time and low time jitter. When it is fired by a conventional capacitive discharge unit (CDU), the firing circuit has low inductance and resistance. Because of its low profile structure, it can be easily integrated with the bridge foil used in a conventional exploding foil initiator system (EFIS).
基金Project supported by the National Natural Science Foundation of China for Excellent Young Scholars(Grant No.51422201)the National Natural Science Foundation of China(Grant Nos.51172041,51372035,11304035,61574031,and 61404026)+4 种基金the National Basic Research Program of China(Grant No.2012CB933703)the"111"Project,China(Grant No.B13013)the Fund from Jilin Province,China(Grant Nos.20140520106JH and 20140201008GX)the Research Fund for the Doctoral Program of Higher Education,China(Grant No.20130043110004)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2412015KJ008 and 2412016KJ003)
文摘In this study, the unipolar resistive switching （URS） and bipolar resistive switching （BRS） are demonstrated to be coexistent in the Ag/ZnO/Pt memory device, and both modes are observed to strongly depend on the polarity of forming voltage. The mechanisms of the URS and BRS behaviors could be attributed to the electric-field-induced migration of oxygen vacancies （Vo） and metal-Ag conducting filaments （CFs） respectively, which are confirmed by investigating the temperature dependences of low resistance states in both modes. Furthermore, we compare the resistive switching （RS） characteristics （e.g., forming and switching voltages, reset current and resistance states） between these two modes based on Vo- and Ag-CFs. The BRS mode shows better switching uniformity and lower power than the URS mode. Both of these modes exhibit good RS performances, including good retention, reliable cycling and high-speed switching. The result indicates that the coexistence of URS and BRS behaviors in a single device has great potential applications in future nonvolatile multi-level memory.
基金Project supported by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU),China(Grant No.155-QP-2016)the Fundamental Research Funds for the Central Universities of China(Grant No.3102014JCQ01032)the 111 Project of China(Grant No.B08040)
文摘Bipolar resistance switching characteristics are investigated in Cu/sputtered-HfO_2/Pt structure in the application of resistive random access memory（RRAM）.The conduction mechanism of the structure is characterized to be SCLC conduction.The dependence of resistances in both high resistance state（HRS） and low resistance state（LRS） on the temperature and device area are studied.Then,the composition and chemical bonding state of Cu and Hf at Cu/HfO_2 interface region are analyzed by x-ray photoelectron spectroscopy（XPS）.Combining the electrical characteristics and the chemical structure at the interface,a model for the resistive switching effect in Cu/HfO_2/Pt stack is proposed.According to this model,the generation and recovery of oxygen vacancies in the HfO_2 film are responsible for the resistance change.
文摘We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11004235,11274363,51072224,and 11134007)the National Basic Research Program of China (Grant No. 2009CB930803)the Alexander von Humboldt Foundation (for S.D.S)
文摘Electric-field-induced resistance switching （RS） phenomena have been studied for over 60 years in metal/dielectrics/metal structures. In these experiments a wide range of dielectrics have been studied including binary transition metal oxides, perovskite oxides, chalcogenides, carbon- and silicon-based materials, as well as organic materials. RS phenomena can be used to store information and offer an attractive performance, which encompasses fast switching speeds, high scalability, and the desirable compatibility with Si-based complementary metal-oxide-semiconductor fabrication. This is promising for nonvolatile memory technology, i.e., resistance random access memory （RRAM）. However, a comprehensive understanding of the underlying mechanism is still lacking. This impedes faster product development as well as accurate assessment of the device performance potential. Generally speaking, RS occurs not in the entire dielectric but only in a small, confined region, which results from the local variation of conductivity in dielectrics. In this review, we focus on the RS in oxides with such an inhomogeneous conductivity. According to the origin of the conductivity inhomogeneity, the RS phenomena and their working mechanism are reviewed by dividing them into two aspects： interface RS, based on the change of contact resistance at metal/oxide interface due to the change of Schottky barrier and interface chemical layer, and bulk RS, realized by the formation, connection, and disconnection of conductive channels in the oxides. Finally the current challenges of RS investigation and the potential improvement of the RS performance for the nonvolatile memories are discussed.
文摘In this work, we investigated resistive switching behavior of CrO<sub>x</sub> thin films grown by using sputtering technique. Conventional I-V measurements obtained from Ag/CrO<sub>x</sub>/Pt/Ti/SiO<sub>2</sub>/Si structures depict the bipolar switching behavior, which is controlled by formation/dissolution processes of Ag conducting filaments through electrochemical redox reaction under external electric field driven. Conductive atomic force microscopy (C-AFM) technique provides the valuable mapping images of existing Ag filaments at low resistance state as well as the characteristics of filament distributions and diameters. This study also reveals that where the higher amplitude of topography is, the easier possibility of forming conducting filament paths is on CrO<sub>x</sub> surface films.
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National Natural Science Foundation of China(No.71401144)
文摘It is important to consider the changing states in hedging.The Markov regime-switching dynamic correlation multivariate stochastic volatility( MRS-DC-MSV) model was proposed to solve this issue. DC-MSV model and MRS-DC-MSV model were used to calculate the time-varying hedging ratios and compare the hedging performance. The Markov chain Monte Carlo( MCMC) method was used to estimate the parameters. The results showed that,there were obviously two economic states in Chinese financial market. Two models all did well in hedging,but the performance of MRS-DCMSV model was better. It could reduce risk by nearly 90%. Thus,in the hedging period,changing states is a factor that cannot be neglected.
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.
