ORCID Profile
0000-0001-9003-9299
Current Organisation
Tianjin University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 2010
Publisher: IOP Publishing
Date: 10-2011
Abstract: Analysis of asymmetric current–voltage ( I – V ) of low resistance state (LRS) and high resistance state (HRS) in a W/Pr 0.7 Ca 0.3 MnO 3 (PCMO) submicron (φ250 nm) resistive memory device revealed the formation of a Schottky-like contact in both states. Raman spectroscopy analysis was used to measure the concentration of oxygen vacancies in LRS and HRS. A significant intensity difference at ∼610 cm -1 for HRS and LRS indicates that a higher number of oxygen vacancies are created in HRS than in LRS. Based on material analysis, modulation of the oxygen vacancy concentration at the PCMO layer in relation to the redox reaction between W and Mn proposed to be responsible for resistive switching phenomena.
Publisher: IOP Publishing
Date: 04-2011
Abstract: Resistive switching characteristics of bilayered titanium oxides layer were investigated. To improve the relatively poor electrical characteristics of solution-processed TiO x active layers, we incorporated an additional thin TiO 2 (∼8 nm) layer by atomic layer deposition. The bilayered titanium oxide active layer showed a significantly improved performance, such as a larger ON/OFF ratio, a stable resistive switching over 100 times under a dc voltage sweep, cell-to-cell uniformity, and high device yield ( %). These improved properties can be explained by the transition of the resistive switching mechanism from filamentary switching through the defective side in solution-processed TiO x to interfacial switching resulting from the oxygen ion migration between two active layers.
Publisher: IOP Publishing
Date: 11-07-2018
Abstract: The threshold switching behavior of Pt/NbO
Publisher: Elsevier BV
Date: 05-2004
Publisher: IOP Publishing
Date: 07-12-2021
Abstract: Volatile memristors, or threshold switching devices, exhibit a erse range of negative differential resistance (NDR) characteristics under current-controlled operation and understanding the origin of these responses is of great importance for exploring their potential as nano-scale oscillators for neuromorphic computing. Here we use a previously developed two-zone, parallel memristor model to undertake a systematic analysis of NDR modes in two-terminal metal-oxide-metal devices. The model assumes that the non-uniform current distribution associated with filamentary conduction can be represented by a high current density core and a lower current-density shell where the core is assumed to have a memristive response due to Poole-Frenkel conduction and the shell is represented by either a fixed resistor or a second memristive region. A detailed analysis of the electrical circuits is undertaken using a lumped-element thermal model of the core-shell structure, and is shown to reproduce continuous and discontinuous NDR responses, as well as more complex compound behaviour. Finally, an interesting double-window oscillation behaviour is predicted and experimentally verified for a device with compound NDR behaviour. These results clearly identify the origin of different NDR responses and provide a strong basis for designing devices with complex NDR characteristics.
Publisher: IOP Publishing
Date: 15-10-2008
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP44451A
Abstract: We report the influence of zinc oxide (ZnO) seed layers on the performance of ZnO-based memristive devices fabricated using an electrodeposition approach. The memristive element is based on a sandwich structure using Ag and Pt electrodes. The ZnO seed layer is employed to tune the morphology of the electrodeposited ZnO films in order to increase the grain boundary density as well as construct highly ordered arrangements of grain boundaries. Additionally, the seed layer also assists in optimizing the concentration of oxygen vacancies in the films. The fabricated devices exhibit memristive switching behaviour with symmetrical and asymmetrical hysteresis loops in the absence and presence of ZnO seed layers, respectively. A modest concentration of oxygen vacancy in electrodeposited ZnO films as well as an increase in the ordered arrangement of grain boundaries leads to higher switching ratios in Ag/ZnO/Pt devices.
Publisher: American Chemical Society (ACS)
Date: 24-04-2013
DOI: 10.1021/AM400671N
Publisher: Elsevier BV
Date: 11-2009
Publisher: Wiley
Date: 09-10-2019
Publisher: Wiley
Date: 17-09-2008
Publisher: Springer Science and Business Media LLC
Date: 29-03-2012
Publisher: Springer Science and Business Media LLC
Date: 05-06-2009
Publisher: Elsevier BV
Date: 10-2006
Publisher: IOP Publishing
Date: 20-02-2017
Abstract: The coupling dynamics of capacitively coupled Nb/Nb
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 06-2022
Publisher: IOP Publishing
Date: 09-06-2011
DOI: 10.1088/0022-3727/44/25/255104
Abstract: A transparent resistance random access memory (RRAM) structure consisted of all-ZnO-based film is fabricated by the pulsed laser deposition method at room temperature. The device is based on transparent Mg-doped ZnO films, sandwiched by Al-doped ZnO as electrodes. Reliable and reproducible bipolar resistance memory switching performances are achieved. Fast and stable switching behaviour in the voltage pulse mode is demonstrated with set and reset durations of 50 ns and 100 ns, respectively. The transmittance of the device is from 64% to 82% in the visible region. All-ZnO-based transparent RRAM will open a route towards see-through memory devices.
Publisher: China Science Publishing & Media Ltd.
Date: 10-03-2010
Publisher: American Scientific Publishers
Date: 04-2012
Abstract: Yttria-stabilized zirconia (YSZ) layers of various thicknesses were designed and introduced before Pr0.7Ca0.3MnO3 (PCMO) film was deposited on W bottom electrodes with a submicron via-hole structure. By changing the thickness of the YSZ barrier layer (3, 5, 9, and 13 nm), a tunable memory window can be realized while low power consumption (P(max) 10(3)), die-to-die uniformity, sweeping endurance, and a retention time of more than 10(3) s, can be obtained by optimizing the thickness of YSZ layer.
Publisher: Wiley
Date: 17-05-2018
Publisher: AIP Publishing
Date: 13-11-2017
DOI: 10.1063/1.4999373
Abstract: This study investigates the temperature dependence of current-controlled negative differential resistance (CC-NDR) in Pt/NbOx/TiN devices and its effect on the dynamics of associated Pearson-Anson relaxation oscillators. The voltage range over which CC-NDR is observed decreases with increasing temperature such that no NDR is observed for temperatures above ∼380 K. Up to this temperature, relaxation oscillators exhibit voltage and temperature dependent oscillation frequencies in the range of 1 to 13 MHz. Significantly, the sensitivity of the frequency to temperature changes was found to be voltage-dependent, ranging from 39.6 kHz/K at a source voltage of 2 V to 110 kHz/K at a source voltage of 3 V, in the temperature range of 296–328 K. Such a behaviour provides insights into temperature tolerance and tuning variability for environmentally sensitive neuromorphic computing.
Publisher: The Electrochemical Society
Date: 2009
DOI: 10.1149/1.3129136
Publisher: Elsevier BV
Date: 04-2006
Publisher: Elsevier BV
Date: 10-2011
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2013
Publisher: Wiley
Date: 12-05-2020
Publisher: The Electrochemical Society
Date: 29-08-2012
DOI: 10.1149/2.004205SSL
Publisher: Oxford University Press (OUP)
Date: 08-2014
Publisher: AIP Publishing
Date: 10-2009
DOI: 10.1063/1.3236573
Abstract: The reproducible forming-free resistive switching (RS) behavior in rare-earth-oxide Gd2O3 polycrystalline thin film was demonstrated. The characteristic of this forming-free RS was similar to that of other forming-necessary binary RS materials except that its initial resistance starts from not the high resistance state (HRS) but the low resistance state (LRS). An ultrahigh resistance switching ratio from HRS to LRS of about six to seven orders of magnitude was achieved at a bias voltage of 0.6 V. Mechanism analysis indicated that the existence of metallic Gd in the Gd2O3 films plays an important role in the forming-free RS performance. Our work provides a novel material with interesting RS behavior, which is beneficial to deepen our understanding of the origin of RS phenomenon.
Publisher: AIP Publishing
Date: 12-03-2012
DOI: 10.1063/1.3694016
Abstract: We investigated the effect of a ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin film on the generation of resistive switching in a stacked Pr0.7Ca0.3MnO3 (PCMO)/Nb-doped SrTiO3 (Nb:STO) heterostructure forming a p-n junction. To promote the ferroelectric effect, the thin PZT active layer was deposited on an epitaxially grown p-type PCMO film on a lattice-matched n-type Nb:STO single crystal. It was concluded that the observed resistive switching behavior in the all-perovskite Pt/PZT/PCMO/Nb:STO heterostructure was related to the modulation of PCMO/Nb:STO p-n junction’s depletion width, which was caused either by the PZT ferroelectric polarization field effect, the electrochemical drift of oxygen ions under an electric field, or both simultaneously.
Publisher: IOP Publishing
Date: 10-02-2015
Publisher: American Chemical Society (ACS)
Date: 10-12-2014
DOI: 10.1021/AM404570A
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 05-2012
Publisher: American Chemical Society (ACS)
Date: 08-10-2012
DOI: 10.1021/CM302899V
Publisher: The Electrochemical Society
Date: 2011
DOI: 10.1149/1.3556977
Publisher: Wiley
Date: 09-07-2008
Publisher: The Electrochemical Society
Date: 2010
DOI: 10.1149/1.3494433
Publisher: AIP Publishing
Date: 28-09-2016
DOI: 10.1063/1.4963288
Abstract: Electrical self-sustained oscillations have been observed in a broad range of two-terminal systems and are of interest as possible building blocks for bio-inspired neuromorphic computing. In this work, we experimentally explore voltage-controlled oscillations in NbOx devices with a particular focus on understanding how the frequency and waveform are influenced by circuit parameters. We also introduce a finite element model of the device based on a Joule-heating induced insulator-metal transition. The electroformed device structure is represented by a cylindrical conductive channel (filament) comprised of NbO/NbO2 zones and surrounded by an Nb2O5−x matrix. The model is shown to reproduce the current-controlled negative differential resistance observed in measured current-voltage curves, and is combined with circuit elements to simulate the waveforms and dynamics of an isolated Pearson–Anson oscillator. Such modeling is shown to provide considerable insight into the relationship between the material response and device and circuit characteristics.
Publisher: Elsevier BV
Date: 12-2010
Publisher: Springer Science and Business Media LLC
Date: 22-07-2009
Publisher: Elsevier BV
Date: 07-2011
Publisher: Elsevier BV
Date: 08-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2012
Publisher: IOP Publishing
Date: 28-06-2021
Publisher: IOP Publishing
Date: 04-11-2011
DOI: 10.1088/0957-4484/22/47/475702
Abstract: The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide 1-oxide 2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbO(x)-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbO(x)-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbO(x) bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WO(x)-NbO(x) interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices.
Publisher: Wiley
Date: 07-03-2012
Publisher: Elsevier BV
Date: 04-2012
Publisher: IOP Publishing
Date: 08-05-2008
Publisher: Wiley
Date: 19-01-2011
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 09-2012
Publisher: Elsevier BV
Date: 04-2031
Publisher: Elsevier BV
Date: 04-2013
Publisher: Wiley
Date: 16-07-2015
Publisher: Elsevier BV
Date: 11-2012
Publisher: IOP Publishing
Date: 09-12-2010
DOI: 10.1088/0022-3727/44/1/015302
Abstract: Mg x Zn 1− x O alloy films with Mg concentration ranging from 0 to 0.5 were fabricated by a pulsed laser deposition method. The effect of Mg content on the microstructure and resistive switching behaviour was investigated. It was found that the film structure changed from pure hexagonal to a coexistence of hexagonal and cubic with increasing Mg content from 0 to 0.5. In addition, the ratio of the high-resistance state to the low-resistance state improved from ∼14 to ∼2 × 10 8 . Furthermore, rapid thermal annealing of the s les reduced the forming voltage from ∼18 V to ∼10 V. The resistive switching behaviour in the Mg x Zn 1− x O films was explained by the filament model based on the variation of band gap and crystalline grains induced by the Mg content modulation and the thermal treatment.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Springer Science and Business Media LLC
Date: 30-07-2009
Publisher: Elsevier BV
Date: 02-2009
Publisher: AIP Publishing
Date: 15-09-2011
DOI: 10.1063/1.3633227
Abstract: Resistive switching characteristics of thermally oxidized tungsten thin films and their switching mechanism were investigated, modifying thickness of the active layer (WOx) by varying oxidation conditions. Two types of switching were observed in Pt/WOx/W memory devices. Thinner film (t ≤ 15 nm) exhibits clockwise switching (CWS) with filamentary characteristics, whereas thicker film (t ≥ 25 nm) exhibits counter-clockwise switching (CCWS) with more homogeneous conduction. Both switching modes are highly reliable and show good cycling endurance. The conduction phenomena in two different switching modes were examined. In the case of CWS, the conduction mechanism changes from Schottky emission to ohmic conduction due to the local bypass of Schottky barrier formed at Pt/WOx interface by oxygen vacancies. Contrary to CWS, CCWS showed a completely different conduction mechanism. The high resistance state is dominated by the Schottky emission at low electric field and by Poole–Frenkel emission at high electric field, whereas the low resistance state exhibits the Schottky emission. Different types of switching behavior might be attributed to the non-homogenous defect distribution across the active layer. A possible conduction sketch for two types switching behaviors is also discussed.
Publisher: AMPCo
Date: 10-2011
DOI: 10.5694/MJA11.10825
Publisher: AIP Publishing
Date: 12-09-2011
DOI: 10.1063/1.3638486
Abstract: The concept of memristive filaments (MFs) is introduced, which is based on the memristors developed by the Hewlett–Packard group. The effects of key parameters on electrical properties are elucidated. The current–voltage features of bipolar and filamentary resistive switching are reproduced by using a parallel MF model with dynamic growth and rupture of multiple MFs. This model can be extended and adapted to most nanosized transition metal oxide memristors.
Publisher: IOP Publishing
Date: 20-03-2015
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 28-03-2017
Publisher: AIP Publishing
Date: 02-2022
DOI: 10.1063/5.0073285
Abstract: Nature positively embodies a rich yet complex array of nonlinear phenomena. To date, it has remained unclear how to exploit these phenomena to solve a wide range of problems. The Van der Pol oscillator is one of the nonlinear dynamical systems that hold tremendous promise for a broad range of important applications from a circuit performance booster to hard problem solving to mapping the biological nonlinear dynamics. Here, we theoretically build a Van der Pol oscillator circuit using a NbO2 volatile memristor to perform a systematic analysis of the complex nonlinear dynamic behavior. Three types of oscillation phenomena including period doubling, quasi-period, and chaos are obtained by varying the parallel capacitance and futher distinguished by mathematical analysis, such as fast Fourier transform, Poincaré plots, and plane trajectories of voltage on the memristor. The frequency locking phenomenon of the system is presented to enable a programmable frequency demultiplication. Moreover, the other critical circuit parameters such as DC voltage litude, load resistance, and AC driving frequency are also modulated to understand the nonlinear dynamic behavior of the system. All these analyses provide a viable platform to understand and implement nonlinear systems for a broad range of multifunctional oscillatory devices.
Publisher: Korean Physical Society
Date: 12-08-2011
DOI: 10.3938/JKPS.59.497
Publisher: AIP Publishing
Date: 28-09-2015
DOI: 10.1063/1.4932096
Abstract: A configurable resistive switching response is reported for Pt/Nb/HfO2/Pt devices subjected to different set compliance currents. When operated at a low compliance-current (∼100 μA), devices show uniform bipolar resistive switching behavior. As the compliance current is increased (∼500 μA), the switching mode changes to integrated threshold-resistive (1S1M) switching, and at still higher currents (∼1 mA), it changes to symmetric threshold switching (1S) characteristic of threshold switching in NbO2−δ. These switching transitions are shown to be consistent with the development of an NbO2−δ interlayer at the Nb/HfO2 interface that is limited by the set compliance current due to its effect on oxygen transport and local Joule heating. The proposed mechanism is supported by finite element modeling of the 1S1M response assuming the presence of such an interlayer. These findings help to understand role of interface reactions in controlling device performance and provide a means for the self-assembly of integrated 1S1M resistive random access memory structures.
Publisher: Wiley
Date: 13-08-2013
Publisher: Wiley
Date: 13-08-2009
Publisher: Wiley
Date: 28-08-2019
Publisher: Elsevier BV
Date: 12-2004
Publisher: Wiley
Date: 05-01-2010
Publisher: Elsevier BV
Date: 08-2021
Publisher: AIP Publishing
Date: 26-09-2019
DOI: 10.1063/1.5116777
Abstract: The dynamics of NbO2-based single and coupled oscillators are comprehensively investigated in this study. For single oscillators, the oscillation frequency is shown to have a strong dependence on the source voltage and load resistance. The range of the frequency modulation can be tuned from 2.1 to 6.8 MHz, while the load resistance is fixed at 3 kΩ. For coupled oscillators, rich and complex dynamics including in- and antiphase locking phenomena are carefully explored by using a mutual capacitor. According to different phase trajectories on the phase plane of both voltages across two devices, the evolution of the source voltage vs coupling capacitance phase diagram is shown with load resistance mismatch. Four coupling regions in the phase diagram are recognized, including a butterfly-shaped coupling zone, a linear coupling zone, a transition zone, and an uncoupled zone. As the load resistance mismatch increases from 1.0% to 3.9%, the linear coupling zone gradually disappears while the butterfly-shaped coupling zone gradually expands. When the load resistance mismatch is larger than 9.5%, the butterfly-shaped coupling zone gradually decreases while the uncoupled zone enlarges significantly.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B912324E
Publisher: Wiley
Date: 13-12-2007
Publisher: Elsevier BV
Date: 06-2007
Publisher: AIP Publishing
Date: 22-06-2020
DOI: 10.1063/5.0004139
Abstract: Neuromorphic computing based on spikes has broad prospects in energy-efficient computation. Memristive neuron in this study is composed of two volatile memristors that have been shown to exhibit rich biological neuronal dynamics. Here, we show spiking dynamic behaviors of NbO2 memristive neurons by a detailed simulation study. With a DC input voltage, the operation windows of both periodic oscillation and neuron-like action potential spikes are recognized in the resistance–voltage phase diagrams of NbO2 memristive neurons. With a voltage pulse as the input, the periodic oscillation region can be classified into three subregions including the spike-OFF, spike-ON, and meta-spike transition regions. When the memristive neuron operates in the meta-spike transition region, it can regulate the “ON” and “OFF” states of the oscillation circuit by changing the ending time of the input pulse. It implies that both the input signal and the output signal determine the state of the circuit. The demonstration of a phase matching method provides a useful way for controlling “ON” and “OFF” states of the periodic oscillation behavior of the memristive neuron. Moreover, the effect of the circuit parameters on the peak-to-valley litude of the output spikes with action potential is investigated. A stable and controllable waveform output can be regulated by changing the capacitance, incorporating a series resistor, and customizing the active memristor. All these results provide a reliable reference for implementing memristive neurons in neuromorphic computing.
Publisher: IOP Publishing
Date: 25-11-2010
DOI: 10.1088/0022-3727/43/49/495104
Abstract: The resistive switching characteristics of Pt/TiO 2 /W devices in a submicrometre via-hole structure are investigated. TiO 2 film is grown by the sol–gel spin coating technique. The device exhibits reversible and reproducible bistable resistive switching with a rectifying effect. The Schottky contact at the Pt/TiO 2 interface limits electron injection under reverse bias resulting in a rectification ratio of at 2 V in the low-resistance state. The switching mechanism in our device can be interpreted as an anion migration-induced redox reaction at the tungsten bottom electrode (W). The rectifying effect can significantly reduce the sneak path current in a crossbar array and provide a feasible way to achieve high memory density.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2014
Publisher: Wiley
Date: 19-08-2011
Publisher: IEEE
Date: 06-2012
Publisher: Elsevier BV
Date: 06-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM32281A
Publisher: IOP Publishing
Date: 11-08-2009
Publisher: Wiley
Date: 09-2011
Abstract: We propose a homogeneous nanoscaled (∅︁ 250 nm) bilayered Pr 0.7 Ca 0.3 MnO 3 (PCMO)‐based memory device that exhibits low power and good memristive switching behavior. Accurate control of the oxygen‐deficient (PCMO 3– x ) layer thickness promotes oxygen migration between PCMO 3– x and stoichiometric PCMO (PCMO 3 ). The bilayered PCMO structure was confirmed by X‐ray photoelectron spectroscopy analysis. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: AIP Publishing
Date: 15-05-2011
DOI: 10.1063/1.3583669
Abstract: Reversible and controllable conversion between unipolar and bipolar resistive switching (URS and BRS) was observed in Pt/TiO2/Pt memory devices. The URS and BRS of this device exhibited different low resistance states but shared the same high resistance state. The conduction mechanisms of low resistance states in URS and BRS are Ohmic conduction and electrons tunneling, respectively, while the high resistance state is controlled by Schottky barrier formed at the top interface of Pt/TiO2. The temperature dependence of resistance states indicates Magnéli phase filaments formed in URS. A unified model was then proposed to demonstrate the unification of filament and interfacial switching mechanisms.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Elsevier BV
Date: 07-2012
Publisher: American Physical Society (APS)
Date: 29-12-2015
Publisher: American Physical Society (APS)
Date: 09-06-2020
Publisher: AIP Publishing
Date: 25-05-2015
DOI: 10.1063/1.4921745
Abstract: Electrical self-oscillation is reported for a Ti/NbOx negative differential resistance device incorporated in a simple electric circuit configuration. Measurements confirm stable operation of the oscillator at source voltages as low as 1.06 V, and demonstrate frequency control in the range from 2.5 to 20.5 MHz for voltage changes as small as ∼1 V. Device operation is reported for & .5 × 1010 cycles, during which the operating frequency and peak-to-peak device current decreased by ∼25%. The low operating voltage, large frequency range, and high endurance of these devices makes them particularly interesting for applications such as neuromorphic computing.
Publisher: The Electrochemical Society
Date: 2011
DOI: 10.1149/1.3505098
Publisher: The Electrochemical Society
Date: 2011
DOI: 10.1149/1.3617442
Location: Korea, Republic of
No related grants have been discovered for Xinjun Liu.