N-type Negative Differential Resistance Research Articles

The Effect of Temperature on a Single-Electron Transistor I-V Curve

In this paper, the effect of temperature on Single-Electron Transistor (SET) electrical behavior is investigated. In particular, a study of the current-voltage (I-V) curves according to parameter (temperature and gate voltage) variation is presented. Among others, the interesting phenomenon of the N-type negative differential resistance is reported as the temperature increases from absolute zero (0 K) to room temperature. Finally, theoretical analysis and simulation shows that the choice of the appropriate temperature and gate-voltage combination the SET I-V curves demonstrates either a negative differential resistance region, a switching effect, or a simple resistance behavior.

Evolution between RS and NRS behaviors in BiFeO3@egg albumen nanocomposite based memristor

The coupling of resistance switching (RS) behavior and N-type negative differential resistance (NDR) effect provides a promising physical basis for the preparation of low-power and multifunctional electronic devices. N-type NDR effect can be expressed by the relationship between peak voltage (VP), valley voltage (VV) and the homologous current (IP, IV). In this work, a memristive device with Ag/BFO@EA/FTO structure was prepared by inserting BiFeO3 (BFO) nanoparticles into egg albumen (EA) as the functional layer, and observed the evolution between RS and NDR coupled RS (NRS) behaviors with the regulation of applied voltage window. Besides, it can be observed a wide current gap of 18.6 mA between IP and IV in the narrow voltage gap (about 0.4 V) between VP and VV, indicating that the device has low power consumption and fast reading/writing speed when it is applied to information processing. Finally, based on the obtained data, it was deeply analyzed the mechanism of NRS effect in the Ag/BFO@EA/FTO memristive device. Therefore, this work provides a new perspective for realizing multi-level storage and multifunctional advanced applications in the memristive device.

Improved resistive switching performance and mechanism analysis of MoO3 nanorods based memristors

Low dimensional nanomaterials have distinctive physical, chemical, and electrical characteristics, which have led to their widespread use in the preparation of sensors, optoelectronic devices, and nonvolatile memory devices in recent years. MoO3 nanomaterials are transition metal oxides with high work functions and broadband gaps, which have potential applications in electronic, electrochromic, and battery devices. In this work, Ag/MoO3/Ti memristive device was prepared by annealing MoO3 nanospheres, which can improve resistive switching (RS) behavior. In other words, one-dimensional (1D) MoO3 nanorods with uniform size and dense connections was obtained by annealing MoO3 nanospheres at 300 ℃. The RS behavior of the Ag/MoO3/Ti memristor presents obvious nonvolatile memory characteristics with larger resistance window at room temperature. In particular, the device shows N-type negative differential resistance (NDR) effect at relatively high positive voltage region. Based on the obtained data, the RS behavior conduction mechanism of the Ag/MoO3/Ti device was discussed by establishing physical models of Ohmic conduction and Schottky emission. This work establishes the foundation for further understanding the working mechanisms of memristors and exploring potential applications of low dimensional material based memristors.

Theoretical Prediction of Semiconductor-Free Negative Differential Resistance Tunnel Diodes with High Peak-to-Valley Current Ratios Based on Two-Dimensional Cold Metals

The negative differential resistance (NDR) tunnel diodes are promising alternative devices for beyond-CMOS (complementary metal oxide semiconductor) computing because they offer several potential applications when integrated with transistors. We propose a semiconductor-free NDR tunnel diode concept that exhibits an ultrahigh peak-to-valley current ratio (PVCR) value. Our proposed NDR diode consists of two cold metal electrodes separated by a thin insulating tunnel barrier. The NDR effect stems from the unique electronic band structure of the cold metal electrodes; i.e., the width of the isolated metallic bands around the Fermi level as well as the energy gaps separating higher- and lower-lying bands determine the current–voltage (I–V) characteristics and the PVCR value of the tunnel diode. By proper choice of the cold metal electrode materials, either a conventional N-type or Λ-type NDR effect can be obtained. Two-dimensional (2D) nanomaterials offer a unique platform for the realization of proposed NDR tunnel diodes. To demonstrate the proof of concept, we employ the nonequilibrium Green function method combined with density functional theory to calculate the I–V characteristic of the lateral (AlI2/MgI2/AlI2) and vertical (NbS2/h-BN/NbS2) heterojunction tunnel diodes based on 2D cold metals. For the lateral tunnel diode, we obtain a Λ-type NDR effect with an ultrahigh PVCR value of 1016 at room temperature, while the vertical tunnel diode exhibits a conventional N-type NDR effect with a smaller PVCR value of about 104. The proposed concept provides a semiconductor-free solution for NDR devices to achieve the desired I–V characteristics with ultrahigh PVCR values for memory and logic applications.

Magnetic Full Adder Based on Negative Differential Resistance-Enhanced Anomalous Hall Effect

Spintronic logic devices have attracted attention because of the prospect of breaking the von Neumann bottleneck through nonvolatile in-memory computing. Although varieties of spin Boolean logic gates have been proposed, spintronic arithmetic logic units such as adders have not been extensively studied because of the difficulties in application of the cascade method of CMOS-based logic in spintronic devices. We experimentally demonstrated a spintronic full adder based on the anomalous Hall effect and geometrical tuning magnetization switching driven by spin-orbit torque. The anomalous Hall effect of magnetic bits was enhanced by nonlinear elements with N-type negative differential resistance to control the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on/off</small> state of <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s, which determined the write voltage of the memory unit. The magnetizations of the memory bits in the memory unit were switched one by one as write voltage increased because of geometry difference. The order of magnetization switching caused the response of the anomalous Hall voltage of the memory unit to the input configurations to conform with the logic function of the full adder. The computation function of the full adder combined with memory writing was experimentally realized with only seven magnetic bits and two steps. The reduced number of magnetic bits and time steps indicated the efficiency of space and time of our device, which is beneficial for practical applications.

Transverse barrier formation by electrical triggering of a metal-to-insulator transition

Application of an electric stimulus to a material with a metal-insulator transition can trigger a large resistance change. Resistive switching from an insulating into a metallic phase, which typically occurs by the formation of a conducting filament parallel to the current flow, is a highly active research topic. Using the magneto-optical Kerr imaging, we found that the opposite type of resistive switching, from a metal into an insulator, occurs in a reciprocal characteristic spatial pattern: the formation of an insulating barrier perpendicular to the driving current. This barrier formation leads to an unusual N-type negative differential resistance in the current-voltage characteristics. We further demonstrate that electrically inducing a transverse barrier enables a unique approach to voltage-controlled magnetism. By triggering the metal-to-insulator resistive switching in a magnetic material, local on/off control of ferromagnetism is achieved using a global voltage bias applied to the whole device.

Effects of top electrode material in hafnium-oxide-based memristive systems on highly-doped Si

This work provides useful insights into the development of HfO2-based memristive systems with a p-type silicon bottom electrode that are compatible with the complementary metal–oxide–semiconductor technology. The results obtained reveal the importance of the top electrode selection to achieve unique device characteristics. The Ag/HfO2/Si devices have exhibited a larger memory window and self-compliance characteristics. On the other hand, the Au/HfO2/Si devices have displayed substantial cycle-to-cycle variation in the ON-state conductance. These device characteristics can be used as an indicator for the design of resistive-switching devices in various scenes such as, memory, security, and sensing. The current–voltage (I–V) characteristics of Ag/HfO2/Si and Au/HfO2/Si devices under positive and negative bias conditions have provided valuable information on the ON and OFF states of the devices and the underlying resistive switching mechanisms. Repeatable, low-power, and forming-free bipolar resistive switching is obtained with both device structures, with the Au/HfO2/Si devices displaying a poorer device-to-device reproducibility. Furthermore, the Au/HfO2/Si devices have exhibited N-type negative differential resistance (NDR), suggesting Joule-heating activated migration of oxygen vacancies to be responsible for the SET process in the unstable unipolar mode.

Electronic Transport and Resonant Tunneling Properties of Hyperbolic Pöschl-Teller Double-Barrier Structures

The ballistic electron transport characteristics of hyperbolic Pöschl-Teller double-barrier resonant tunneling structures are investigated. The transmission coefficient and the current density-voltage characteristic in electrically biased one dimensional hyperbolic Pöschl-Teller double-barrier structures with different structure parameters have been calculated by using non-equilibrium Green’s function method. Results for the transmission coefficients and the current densities are compared with the barrier shapes. The results show that the widths of the wells and heights of barriers have a significant effect on the transmission properties. The current density-voltage characteristic presents N-type negative differential resistance.

Novel five-state latch using double-peak negative differential resistance and standard ternary inverter

We propose complement double-peak negative differential resistance (NDR) devices with ultrahigh peak-to-valley current ratio (PVCR) over 106 by combining tunnel diode with conventional CMOS and its compact five-state latch circuit by introducing standard ternary inverter (STI). At the “high”-state of STI, n-type NDR device (tunnel diode with nMOS) has 1st NDR characteristics with 1st peak and valley by band-to-band tunneling (BTBT) and trap-assisted tunneling (TAT), whereas p-type NDR device (tunnel diode with pMOS) has second NDR characteristics from the suppression of diode current by off-state MOSFET. The “intermediate”-state of STI permits double-peak NDR device to operate five-state latch with only four transistors, which has 33% area reduction compared with that of binary inverter and 57% bit-density reduction compared with binary latch.

Negative differential resistance, rectifying performance and switching behaviour in carbon-chain based molecular devices

Using non equilibrium Green's function formalism coupled with density functional theory, we carry out electronic transport calculation in two types of molecular devices, one constructed by linear monoatomic carbon chain (···C–C–C–C ···) and the other by two carbon chains capped with a phenyl ring (···C–C–Ph–C–C···), sandwiched between two z-shape electrodes, constructed by zigzag-armchair-zigzag (zz-ac-zz) graphene nanoribbons (GNRs). The potential difference between the z-shape contacts can be varied by employing an external d.c. voltage source. Thus, one may observe the variation of conductivity through the channels. The current–voltage (I–V) characteristics of the proposed resistors show N-type negative differential resistance (NDR), within a particular voltage region. The figure of merit or PVR (peak to valley) ratio (Ipeak/Ivalley) gets significantly increased, on capping the chains with phenyl ring. A higher value of PVR in I–V characteristics enhances the possibility of applications utilizing NDR. The calculated I–V characteristic is asymmetric and the rectification ratio is found to be 7, in case of the linear carbon chain.The rectification ratio R(V) = I(V)/I(−V) is an important parameter which determines, its suitability as rectifying device. It has been demonstrated that on varying the conformation of the phenyl ring with respect to the plane of electrodes, the transport properties of the system can be modulated. Interestingly, I–V characteristics are asymmetric and show dual NDR peaks in perpendicular conformation of the phenyl ring, with respect to the electrodes in the (···C–C–Ph–C–C···) system. The figure of merit is found to be respectively 8 and 51 for the first and second NDR regions. The later value is extremely high, making it an excellent candidate for potential applications. Moreover, the multi peak NDR device may be widely used in multiple-valued logics. Only a limited number of multiple NDR peak molecular-based nano systems have so far been reported, which are quite complex; by contrast the present system seems to be quite simple. The physical phenomenon of NDR was explained in the light of molecular projected self-consistent Hamiltonian (MPSH) and also the evolution of the frontier molecular orbitals (HOMO–LUMO) as well as transmission under various external bias voltages.

Electrical Switching in Thin Film Structures Based on Transition Metal Oxides

Electrical switching, manifesting itself in the nonlinear current-voltage characteristics with S- and N-type NDR (negative differential resistance), is inherent in a variety of materials, in particular, transition metal oxides. Although this phenomenon has been known for a long time, recent suggestions to use oxide-based switching elements as neuristor synapses and relaxation-oscillation circuit components have resumed the interest in this area. In the present review, we describe the experimental facts and theoretical models, mainly on the basis of the Mott transition in vanadium dioxide as a model object, of the switching effect with special emphasis on the emerging applied potentialities for oxide electronics.

N-type negative differential resistance, hysteresis, and oscillations in the current-voltage characteristics of microwave diodes

The dc current-voltage characteristics of microwave diodes are experimentally studied on simultaneous exposure of the diodes to a high-frequency (100 MHz) high-amplitude harmonic signal. In the current-voltage characteristics of the microwave diodes, regions of N-type negative differential resistance, hysteresis, and current oscillations are observed depending on the amplitude and frequency of the high-frequency signal. A comparative analysis of the experimentally observed effects is performed, and possible mechanisms for the effects are discussed.

Absolute negative resistance and multivaluedness on current-voltage characteristics of tunnel diodes

The effect of external perturbations of large amplitude in the form of a coherent signal or noise on the behavior of dynamic and static current-voltage (I–V) characteristics of tunnel diodes has been experimentally investigated. It is shown that, when an appropriate frequency is chosen, an increase in the amplitude of the external coherent signal leads to the occurrence of multivaluedness and absolute negative resistance on the I–V characteristics of tunnel diodes. The noise effect suppresses the N-type negative differential resistance on the I–V characteristics of tunnel diodes and significantly distorts these characteristics. A possible mechanism of the occurrence of absolute negative resistance is proposed.

Electrical and optical properties of hydrated amorphous vanadium oxide

Electrical and optical properties of amorphous vanadium oxide thin films obtained by electrochemical anodic oxidation are studied. It is shown that under cathodic polarization the hydrogen insertion into vanadium oxide from an electrolyte occurs. Metal–insulator transition in amorphous HxVO2 is found to be preserved up to high concentration (x ∼ 1.5) of hydrogen. Memory switching with the N-type negative differential resistance, associated with the H+ ionic transfer, is observed in ‘V/hydrated amorphous vanadium oxide/Au’ sandwich structures.

Nonlocal Complex Ginzburg-Landau Equation for Electrochemical Systems

By means of an extended center-manifold reduction, we derive the nonlocal complex Ginzburg-Landau equation (NCGLE) valid for electrochemical systems with migration coupling. We carry out the stability analysis of the uniform oscillation, elucidating the role of the nonlocal coupling in electrochemical systems at the vicinity of a supercritical Hopf bifurcation. We apply the NCGLE to an experimental system, an N-type negative differential resistance electrochemical oscillator, which is shown to exhibit electrochemical turbulence for wide parameter ranges.

The external-pulse introduced pattern in a system with a closer reference electrode and a quasi-one-dimensional ribbon working electrode

In the present work the electrochemical pattern formation was investigated during electro-oxidation of formic acid on platinum electrode. The working electrode is quasi-one-dimensional ribbon polycrystalline platinum. The stationary domains (sDs) have been successfully captured after an external pulse was triggered. At a relatively high conductivity a new kind of electrochemical pattern was found and it is named as cyclopean pattern. In a nonlinear electrochemical system with an N-type negative differential resistance, the theoretical simulation of the spatial temporal structure is able to predict the existence of stationary domains. Increasing the electrolyte conductivity promotes the formation of stationary domains and cyclopean pattern. The difference of the potential amplitudes in two phases (domains) becomes smaller in an electrolyte with a higher conductivity.

Current instability in a planar gas discharge system with a large-diameter semiconductor cathode

The current instability in a planar gas discharge system is studied experimentally in a wide range of the gas pressure, p (44–550 Torr), interelectrode distance, d (45–330 µm), and diameter, D (5, 9, 12, 18, 22 mm), of the electrode areas of the semiconductor cathodes. While being driven with a stationary voltage, it generates current instabilities with different amplitudes of the oscillation. Through spatially uniform irradiation of the semiconductor cathode, non-stationary states which are non-homogeneous can be generated in a system. It is shown that under the experimental conditions the discharge gap played only a passive role and was not responsible for the appearance of the current instability. At the same time, for different diameters, D, of the electrode an expanded range of current oscillations is observed. The pronounced N-type negative differential resistance is observed in the current–voltage characteristic of a planar gas discharge system with a large-diameter semiconductor cathode.

Light-controllable room temperature negative differential resistance in deep-trench type nitride–oxide tunneling device and its applications

This study presents the room-temperature operation of deep-trench type nitride–oxide metal–insulator–semiconductor three-terminal tunneling devices which were fabricated by a standard metal–oxide–semiconductor process. It is instructive to observe a photoinduced N-type negative differential resistance (NDR) with a high peak-to-valley current ratio for device operated under negative polysilicon node bias under tungsten lamp illumination. An explanation was provided for the NDR phenomenon with proper three-terminal biasing. The sudden current drop under light illumination was caused by the sudden reduction of the two-carrier conduction due to Esaki band-to-band tunneling. The NDR amplitude could be modulated by light intensity. The position of the NDR current peak was tunable at different voltages with different p-well biases. The optoelectronic response of nitride–oxide devices we investigate here may open an application window for the nitride–oxide system in silicon-based optoelectronic integrated circuits, wireless communications, and future quantum devices.

Negative differential resistance in thin-film electroluminescent emitters based on zinc sulfide

S-and N-type negative differential resistance (NDR) has been observed in thin-film electroluminescent emitters based on zinc sulfide doped with manganese, and conditions for its emergence have been identified. It has been found that when a negative half-wave of voltage is applied to the nontransparent top electrode, an S-type NDR with a region of decreasing current is observed, and when it is applied to the transparent bottom electrode, the NDR will be N-type. The emergence of NDR is due to space charges which form in the near-cathode and near-anode layers of the phosphor.

Monolithic integration of resonant tunneling diodes and FET's for monostable-bistable transition logic elements (MOBILE's)

A MOBILE (monostable-bistable transition logic element), employing two n-type negative differential resistance devices connected in series, is a functional logic gate with the advantages of multiple inputs and multiple functions. In this paper, a novel approach to achieve MOBILE operation is demonstrated using monolithic integration of resonant tunneling diodes (RTD) and FETs. In our new integration structure, an RTD and FET are connected in parallel. This structure offers several advantages including separate optimization of RTD's and FET's, and flexible circuit design abilities. For a single-input MOBILE gate, inverter operation at room temperature is demonstrated as the evidence of monostable-to-bistable transition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>