Single-electron Devices Research Articles

Magnetotransport in the quantum wires comprised of vertically stacked quantum dots

We investigate a periodic system of vertically stacked InAs/GaAs quantum dots (VSQD) subjected to a two-dimensional confining harmonic potential and a magnetic field in the symmetric gauge. Given the tiny length scales, adequate lateral confinement, and strong vertical coupling involved in the experiments, the VSQD system has become known for mimicking the standard semiconducting quantum wires. An exact analytical diagnosis of the problem allows us to show the system's direct relevance to the physics of musical sounds, magnetization, magnetotransport, and the designing of the optical amplifiers. The results suggest making the most of the system for applications in single-electron devices and quantum state transfer in the quantum computation and quantum communication networks.

Measuring of an unknown voltage by using single electron transistor based voltmeter

In engineering and science, high operating speed, low power consumption, and high integration density equipment are financially indispensable. Single electron device (SED) is one such equipment. SEDs are capable of controlling the transport of only one electron through the tunneling transistor. It is single electron that is sufficient to store information in SED. Power consumed in the single electron circuit is very low in comparison with CMOS circuits. The processing speed of single electron transistor (SET) based device will be nearly close to electronic speed. SET attracts the researchers, scientists or technologists to design and implement large scale circuits for the sake of the consumption of ultra-low power and its small size. All the incidences for the case of a SET-based circuit happen when only a single electron tunnels through the transistors under the proper applied bias voltage and a small gate voltage or multiple gate voltages. For implementing a single electron transistor based voltmeter circuit, SET would be the best candidate to fulfil the requirements of it. Ultra-low noise is generated during tunneling SEDs. A D Flip-Flop is implemented and based on this, two kinds of registers like sequence register and сode register are made.

Toward high-performance multifunctional electronics: Knitted fabric-based composite with electrically conductive anisotropy and self-healing capacity

Textile-based electronics characterizing easy integration into textile garments and good wearability have received considerable attentions. However, it is still a huge challenge to integrate multiple functions into single electronic device, especially for those having different even opposite requirements in electrical properties. In this work, an anisotropic electrically conductive composite was prepared by encapsulating conductive knitted fabric (CKF) into polyurethane (PU). Based on anisotropic electrical conductivity, i.e., extremely low and stable resistivity in the coursewise direction and significant variation of resistivity in the walewise direction during tensile strains, the composite could efficiently integrate the electro-heating and strain-sensing functions that required opposite electrical properties. When applied for electro-heating applications in the coursewise direction, the CKF/PU composite exhibited fast thermal response, ultrahigh electric-thermal conversion (140 °C at 4 V), and stable electrothermal performance under a large strain (40%) or after long-term use (>1000 stretching cycles). When applied for strain-sensing applications in the walewise direction, the composite showed good sensing performances, including high sensitivity (GF of −8.1 at a 5% strain), low hysteresis, good reproducibility and stability (>1000 cycles), which enabled the device as a wearable sensor to accurately detect human joint movements and subtle motions. Furthermore, the self-healing function was exploited for the CKF/PU electronic device, by which the abnormal sensing property could be fully repaired at human body temperature. This work may shed new light on the future development of high-performance multifunctional wearable electronics with the anisotropic conducting feature.

Carbon & boron substituted-Dibenzo[1,4]azaborinine as a quantum dot-based organic molecular single-electron device for high switching speed applications

The present work investigates the carbon & boron substituted-Dibenzo[1,4]azaborinine molecule as an island or quantum dot(QD) of an organic molecular single electron device(SED). The ‘carbon & boron substituted-Dibenzo[1,4]azaborinine(C13H9BN) as a QD’ is a modified variant of the acene group organic molecule ‘anthracene(C14H10)’, where boron atom are substitution of dangling hydrogens of middle honeycomb and nitrogen substitution of its parent molecule anthracene. Similar to anthracene, the carbon & boron substituted-Dibenzo[1,4]azaborinine is also made up of three linearly fused benzene rings, and has a planar structure with aromatic character. The carbon & boron substituted-Dibenzo[1,4]azaborinine molecule is considered as a QD owing to its impressive stability and conductance that originate from the aromaticity, making it ideal for low power electronic and high switching speed device applications. The calculations have been carried out using the tools AtomisticToolkit-Virtual Nanolab(ATK-VNL) and Gaussian09 packages, which is based on density functional theory (DFT), non-equilibrium green’s function (NEGF) formalisms and ab-initio approach. The charging energies in both isolated and SED conditions, total energy, and the charge stability diagram (CSD) as a function of bias potentials have been used to evaluate the device's efficiency. In comparison to anthracene based SED and its other acene organic molecular derivative SEDs, the proposed ‘carbon & boron substituted-Dibenzo[1,4]azaborinine as a quantum dot based organic molecular SED’ has high switching speed and power efficiency.

High-yield parallel fabrication of quantum-dot monolayer single-electron devices displaying Coulomb staircase, contacted by graphene

It is challenging for conventional top-down lithography to fabricate reproducible devices very close to atomic dimensions, whereas identical molecules and very similar nanoparticles can be made bottom-up in large quantities, and can be self-assembled on surfaces. The challenge is to fabricate electrical contacts to many such small objects at the same time, so that nanocrystals and molecules can be incorporated into conventional integrated circuits. Here, we report a scalable method for contacting a self-assembled monolayer of nanoparticles with a single layer of graphene. This produces single-electron effects, in the form of a Coulomb staircase, with a yield of 87 ± 13% in device areas ranging from < 800 nm2 to 16 μm2, containing up to 650,000 nanoparticles. Our technique offers scalable assembly of ultra-high densities of functional particles or molecules that could be used in electronic integrated circuits, as memories, switches, sensors or thermoelectric generators.

Design and simulation of charge transport in single-electron transistor using TCAD numerical simulator

The ability to control the electron flow of a MOSFET is decreased due to the quantum mechanical effect when scaled down below 50 nm. Hence, A new field of device research is needed to complete this challenge. A device based on Tunneling phenomena is called a single-electron device. In this paper, the most fundamental single-electron device is a single-electron transistor (SET) designed using visual TCAD with a gate length and width of 2 nm. The channel is ultra-thin with a length of 2 nm and a width of 0.005 nm, and the channel thickness is 0.3 nm. Then a Si quantum dot of size 0.5 × 1.nm2 is used between the island and the gate. Both the Devices are simulated using the Genius Simulator. And it is found that at room temperature, the device with Si dot is more efficient. The device with Si dot has less capacitance and higher charging efficiency than the device without the Quantum dot.

Multiplexed Neurotransmission Emulated by a p–n Cross Nanowire Synaptic Transistor for Satiety, Depression, and Drug Withdrawal

AbstractThis paper presents the first synaptic transistor (ST) that combines crossed p‐type and n‐type semiconductor nanowires (NWs) to form a bipolar conductive channels. The bipolar channel with both electron and hole transport paths enables the emulation of multiplexed neurotransmission of different neurotransmitters in a brain to realize complex neural functions using nanowires. Except for basic synaptic functions, the device demonstrates the potential to distinguish reward‐processing and aversive responses. The opposite polarities of NWs enable emulation of a series of complex neural activities using a single electronic device, such as satiety, depression, and drug withdrawal. The device is applicable to deep convolutional neural networks for electrocardiograms. The new strategy of versatile use of electro‐hydrodynamically printed NWs (e‐NWs) is expected to facilitate emulation of complex neural behaviors, and the realization of future neuromorphic electronics that are capable of these behaviors.

Charge-offset stability of single-electron devices based on single-layered Fe nanodot array

In metal-based single-electron devices (SEDs), charge-offset drift has been observed, which is a time-dependent instability caused by charge noise. This instability is an issue in the application of new information processing devices, such as neural network devices, quantum computing devices (charge sensing), and reservoir computing devices. Therefore, the charge-offset drift in metal-based SEDs needs to be suppressed. However, the charge-offset stability of metal-based SEDs has not been investigated in depth, except in the case of Al and Al2O3 SEDs. In this work, Fe-based SEDs formed by single-layer Fe nanodot arrays embedded in MgF2 were studied with regard to their charge-offset stability. Using devices that produce simple current oscillations, the charge-offset drift (ΔQ0) of Fe-based SEDs was evaluated by focusing on peak shifts of the simple current oscillation over time, despite the use of a multi-dot system. This drift (ΔQ0 ≈ 0.3e) was shown to be much lower than in SEDs with Al-dots and Al2O3 tunnel junctions. Notably, the charge-offset drift in the metal-based SEDs was suppressed using the Fe–MgF2 system. The excellent stability of these devices was attributed to the material properties of the Fe–MgF2 system. Finally, as the Fe nanodot array contained numerous dots, the effect of satellite dots acting as traps on the charge-offset instability was discussed. The findings of this study will be important in future applications of metal-based SEDs in new information processing devices.

Analytical approximations of single-electron device current through non-interacting quantum dot

Abstract The electron transport through single electron transistor (SET) consisting of quantum dot (QD) coupled to two metallic electrodes has been studied by employing the non-equilibrium Green function (NEGF) technique. The QD considered in this study has a single energy level and non-interacting electrons. The current-voltage characteristics of QD has been studied by using Meir-Wingreen expression. In this paper, an analytical approximation of Meir-Wingreen formula has been presented with respect to the following conditions: (1) low-temperature limit, (2) finite temperature limit with finite energy | e − e d | k T , (3) finite temperature limit with finite bias Γ e | V | / 2 K T e d , and at high temperatures. Furthermore, the derived analytical formulae are employed to investigate the effect of device parameters (energy level, tunneling rate “level width”, gate voltage, and temperature) on the current-voltage characteristic of SET.

Single molecule electronic devices with carbon-based materials: status and opportunity.

The field of single molecule electronics has progressed remarkably in the past decades by allowing for more versatile molecular functions and improving device fabrication techniques. In particular, electrodes made from carbon-based materials such as graphene and carbon nanotubes (CNTs) may enable parallel fabrication of multiple single molecule devices. In this perspective, we review the recent progress in the field of single molecule electronics, with a focus on devices that utilizes carbon-based electrodes. The paper is structured in three main sections: (i) controlling the molecule/graphene electrode interface using covalent and non-covalent approaches, (ii) using CNTs as electrodes for fabricating single molecule devices, and (iii) a discussion of possible future directions employing new or emerging 2D materials.

Single-particle and collective excitations in quantum wires comprised of vertically stacked quantum dots: Finite magnetic field

A theoretical investigation has been made of the magnetoplasmon excitations in a quasi-one-dimensional electron system composed of vertically stacked, self-assembled InAs/GaAs quantum dots. The smaller length scales involved in the experiments impel us to consider a perfectly periodic system of two-dimensionally confined InAs quantum dot layers separated by GaAs spacers. Subsequent system is subjected to a two-dimensional confining (harmonic) potential in the [Formula: see text]–[Formula: see text] plane and an applied magnetic field (B) in the symmetric gauge. This scheme defines virtually a system of quantum wire comprised of vertically stacked quantum dots (VSQD). We derive and discuss the Dyson equation, the generalized (nonlocal and dynamic) dielectric function, and the inverse dielectric function for investigating the single-particle and collective (magnetoplasmon) excitations within the framework of (full) random-phase approximation (RPA). As an application, we study the influence of the confinement potential and the magnetic field on the component eigenfunctions, the density of states (DOS), the Fermi energy, the collective excitations, and the inverse dielectric functions. How the B-dependence of DOS validate the VSQD mimicking the realistic quantum wires, the Fermi energy oscillates as a function of the Bloch vector, the intersubband single-particle continuum bifurcates at the origin, a collective excitation emerges and propagates within the gap of the split single-particle continuum, and the alteration in the well- and barrier-widths allows to customize the excitation spectrum in the desired energy range are some of the remarkable features of this investigation. These findings demonstrate, for the very first time, the significance of investigating the system of VSQD subjected to a quantizing magnetic field. Given the edge over the planar quantum dots and the foreseen applications in the single-electron devices and quantum computation, investigating the system of VSQD is deemed vital. The results suggest exploiting magnetoplasmon qubits to be a potential option for implementing the solemn idea of quantum state transfer in devising quantum gates for the quantum computation and quantum communication networks.

0D/2D Heterostructures Vertical Single Electron Transistor

AbstractMixed‐dimensional heterostructures formed by the stacking of 2D materials with nanostructures of distinct dimensionality constitute a new class of nanomaterials that offers multifunctionality that goes beyond those of single dimensional systems. An unexplored architecture of single electron transistor (SET) is developed that employs heterostructures made of nanoclusters (0D) grown on a 2D molybdenum disulfide (MoS2) channel. Combining the large Coulomb energy of the nanoclusters with the electronic capabilities of the 2D layer, the concept of 0D–2D vertical SET is unveiled. The MoS2 underneath serves both as a charge tunable channel interconnecting the electrode, and as bottom electrode for each v‐SET cell. In addition, its atomic thickness makes it thinner than the Debye screening length, providing electric field transparency functionality that allows for an efficient electric back gate control of the nanoclusters charge state. The Coulomb diamond pattern characteristics of SET are reported, with specific doping dependent nonlinear features arising from the 0D/2D geometry that are elucidated by theoretical modeling. These results hold promise for multifunctional single electron device taking advantage of the versatility of the 2D materials library, with as example envisioned spintronics applications while coupling quantum dots to magnetic 2D material, or to ferroelectric layers for neuromorphic devices.

Ultrasensitive bio-detection using single-electron effect

Single-electron devices are capable of detecting changes of the electric field caused by the presence of one single electron in their environment. These devices are optimized to identify the material that is in close contact with them based on the material's internal charge distribution or dipole moment. As an important practical use, they present the possibility of detecting bacteria, viruses, or pathogens. However, their practical use is hampered by their nano-meter size, which is normally an order of magnitude smaller than that of detected species, their very complex fabrication techniques, their cryogenic operational temperature, and the problem of bringing the said species in contact with the single-electron structure. In this document, a large scaled room temperature single-electron structure is introduced, and its ability to distinguish liquids based on their internal dipole moments is demonstrated. The device is a Schottky junction made of PtSi, as the metal contact, and the walls and surfaces of the porous Si, as the semiconductor. The reverse bias current-voltage (IV) characteristic of this device is sensitive to 1 ppm change in the dipole moment of the liquid entering its pores. The simple fabrication, easy testing procedure, high sensitivity, and fast response can make this device an optimized testing kit to identify the given bacteria, viruses, or pathogens dissolved in liquids.

A complete set of logic gates with an identical single-stage structure based on periodic nature of single-electron devices

In this paper, a new method for implementing all two-input logic gates on an identical single-stage structure is proposed. We have used unique characteristics of single-electron transistors, which have periodic output–input relation, to design the gates and implement all two-input logic gates (symmetric/non-symmetric, monotonic/non-monotonic) by a single-stage design including only one single-electron transistor. In conventional monotonic devices, such as BJTs and MOSFETs, implementing non-monotonic logic gates such as XOR and XNOR is impossible with a single-stage circuit and a multistage design is required which leads to more complexity, more chip area and higher power consumption. We present the proposed methodology at first, and then, the details of the designs are investigated. The results are obtained analytically using a new approach named two-potential and then confirmed by numerical methods. Furthermore, important characteristics of the proposed gates such as maximum operating temperature, speed of the gates and frequency limitations, power consumption (static and dynamic) and scaling to other technologies have been investigated. Finally, a general idea has been presented about the application of the introduced approach and gate structures in the field of logic circuit and system designing.

Single-Electron Currents in Designer Single-Cluster Devices.

Atomically precise clusters can be used to create single-electron devices wherein a single redox-active cluster is connected to two macroscopic electrodes via anchoring ligands. Unlike single-electron devices comprising nanocrystals, these cluster-based devices can be fabricated with atomic precision. This affords an unprecedented level of control over the device properties. Herein, we design a series of cobalt chalcogenide clusters with varying ligand geometries and core nuclearities to control their current-voltage (I-V) characteristics in a scanning tunneling microscope-based break junction (STM-BJ) device. First, the device geometry is modified by precisely positioning junction-anchoring ligands on the surface of the cluster. We show that the I-V characteristics are independent of ligand placement, confirming a sequential, single-electron tunneling mechanism. Next, we chemically fuse two clusters to realize a larger cluster dimer that behaves as a single electronic unit, possessing a smaller reorganization energy and more accessible redox states than the monomeric analogues. As a result, dimer-based devices exhibit significantly higher currents and can even be pushed to current saturation at high bias. Owing to these controllable properties, single-cluster junctions serve as an excellent platform for exploring incoherent charge transport processes at the nanoscale. With this understanding, as well as properties such as nonlinear I-V characteristics and rectification, these molecular clusters may function as conductive inorganic nodes in new devices and materials.

Solution-Processable Anion-doped Conjugated Polymer for Nonvolatile Organic Transistor Memory with Synaptic Behaviors

Brain-inspired synaptic transistors have been considered as a promising device for next-generation electronics. To mimic the behavior of a biological synapse, both data processing and nonvolatile memory capability are simultaneously required for a single electronic device. In this work, a simple approach to realize a synaptic transistor with improved memory characteristics is demonstrated by doping an ionic additive, tetrabutylammonium perchlorate (TBAP), into an active polymer semiconductor without using any extra charge storage layer. TBAP doping is first revealed to improve the memory window of a derived transistor memory device from 19 to 32 V (∼68% enhancement) with an on/off current ratio over 103 at VG = -10 V. Through morphological analysis and theoretical calculations, it is revealed that the association of anion with polymers enhances the charge retention capability of the polymer and facilitates the interchain interactions to result in improved memory characteristics. More critically, the doped device is shown to successfully mimic the synaptic behaviors, such as paired-pulse facilitation (PPF), excitatory and inhibitory postsynaptic currents, and spike-rate dependent plasticity. Notably, the TBAP-doped device is shown to deliver a PPF index of up to 204% in contrast to the negligible value of an undoped device. This study describes a novel approach to prepare a synaptic transistor by doping conjugated polymers, which can promote the future development of artificial neuromorphic systems.

A Review on Different Single Electron Devices and Their Comparative Study

Single Electron Devices being one of the nanodevices offers reduced feature size and low power consumption along with unique characteristics. The principle of operation is established upon the quantum mechanical tunneling of a single or few electrons for device switching between conducting and non-conducting state. The present work is a detailed survey on the different Single Electron Devices such as Single Electron Box, Double Tunnel Junction, Single Electron Transistor and Single Electron Turnstile. An overall comparative study of them is also furnished here as a fragment of the study. Keywords: Single Electron Box; Double Tunnel Junction; Single electron transistor; Single Electron Turnstile. Cite this Article: Bidisha Das, Riya Bandyopadhyay, Anamika Saha, Promit Das, Arpita Ghosh. A Review on Different Single Electron Devices and Their Comparative Study. International Journal Digital Communication and Analog Signals . 2020; 6(2): 21–27p.

Statistical correlations of currents flowing through a proximized quantum dot

Statistical properties of the electron transport flowing through nanostructures are strongly influenced by the interactions, geometry of the system and/or by type of the external electrodes. These factors affect not only the average current induced in the system but also contribute to fluctuations in the flux of charges and their correlations. Due to possible applications of the hybrid nano-systems, containing one or more superconducting electrodes, a detailed understanding of the flow of charge and its fluctuations seems to be of primary importance. Coulomb repulsion between electrons usually strongly affect the current-current correlation function. In this work we study the correlations in the charge flow through such interacting quantum dot contacted to one superconducting and two normal electrodes. This set-up allows for analysis of the Andreev scattering events in the correlations of currents flowing between external electrodes and, in particular, gives access to cross-correlations between currents from/to different normal electrodes. Our approach relies on the master equation technique, which properly captures the Coulomb interactions. We study the finite frequency correlations and find the relaxation processes, related to the high frequency charge and low frequency polarisation fluctuations. The multiterminal structure of here studied single electron device allows to analyze a competition between the intra- and inter-channel correlations. In the appropriate limit of the interacting quantum dot embedded between two normal electrodes our calculations quantitatively describe the recent experimental data on the frequency dependent correlations. This shows a promising potential of the method for description of the hybrid systems with superconducting electrode(s).

Performance investigation of nanoscale reversible logic gates designed with SE-TLG Approach

ABSTRACT The progressive shrinking of MOS dimensions confronts critical issues while designing low power consuming computational devices. The Single Electron Technology is one of the emerging technological solutions to cope up with the scaling challenges and support Moore’s law. Apart from the miniaturization, another concern is the energy efficiency of the designed circuit. Use of reversible logic in place of the conventional Boolean logic can serve the purpose. The works so far in this field mainly concentrated upon the application aspect of different reversible gates and reversible circuits rather than proper technological approach or device based design .Different reversible gates such as Fredkin, Toffoli and Double Feynman Gate implementation with Single Electron device and their simulation results are presented in this paper. The power consumption, stability and the size are mainly considered as the different performance metrics. The circuit stability and its temperature dependency is also analysed through the Stability plots generated in SIMON simulator. A new reversible gate PE1 for even parity generating circuits is also proposed along with the supporting simulation results .The design issues and power consumption are compared with the SET-CMOS hybrid-based designs of the same circuits.

Quantum electronics and optics at the interface of solid neon and superfluid helium

We predict a new quantum electronic structure at the interface between two condensed phases of noble-gas elements: solid neon and superfluid helium. An excess electron injected onto this interface self-confines its wavefunction into a nanometric dome structure. Its size varies with pressure and optical transitions cover a broad mid-infrared spectrum. A collection of such electrons can form a classical Wigner crystal resembling a quantum-dot array on a triangular lattice. Under ultrafast laser illumination, this Wigner crystal can exhibit the quantum optical phenomenon of superradiance in the picosecond time scale. The ultralong spin-coherence time and micron-scale deterministic configurability allow the electrons in this system to serve as quantum information carriers. Their spin states can be controlled and readout by on-chip single-electron devices.