Orientation-Dependent Performance Analysis of Benzene/Graphene-Based Single-Electron Transistors

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

First principle study of single electron transistor based on metal-organic complex of dibenzothiophene

We investigate the possibility to implement low-energy consuming binary logic gates by means of charge sensing in electrostatically defined quantum dots (QDs) formed in single electron transistors (SETs). In the proposed logic devices, the input signals are represented by the voltage levels at the SET's gate electrodes, and the output is determined by the electrical current in the charge sensor (CS) circuit. In contrast to previous proposals of SET-based logic, the output signal does not depend on the electrical current through SET, but is defined by its charge configuration in the Coulomb blockade regime. Such a logic implementation suppresses the shot noise without increasing energy consumption.

Charge stability diagram and addition energy spectrum for single-electron transistor based on Ni-dithiolene derivatives

We demonstrate gating and charge sensing functions of a lithographically defined single electron transistor (SET). The electrochemical potential of the SET is modulated by applying a voltage to both the source and drain electrodes. The SET integrated with a double quantum dot (DQD) works as a gate electrode for the DQD. Charge transitions in the DQD are detected by the SET through its charge sensing function. This dual function of the SET is useful for saving space in crowded devices with many gates and charge sensors, toward the integration of multiqubits for quantum computation.

We show the control of a charging energy in chemically assembled nanoparticle single-electron transistors (SETs) by altering the core diameter of Au nanoparticles. The charging energy is a fundamental parameter that decides the operating temperature of SETs. Practical application of SETs requires us to regulate the value of the charging energy by tuning the diameter of quantum dots. In this study, we used 3.0, 5.0 and 6.2 nm diameter synthesized Au nanoparticles as a quantum dot in the SETs. The total capacitances and charging energy of the SETs were evaluated from the rhombic Coulomb diamonds attributed to a single Coulomb island. The capacitance and charging energy matched with a concentric sphere model much better than with a simple sphere model. The operating temperatures of the SETs suggested that a charging energy 2.2 times greater than the thermal energy was required for stable operation, in theory. These results will help us to select an appropriate core diameter for the Au nanoparticles in practical SETs.

Ferromagnetic single electron transistor

The single electron transistor (SET) is a nanometer-size device that turns on and off again every time one electron is added to it. In this article, the physics of the SET is reviewed. The consequences of confining electrons to a small region of space are that both the charge and energy are quantized. We review how the charge states and energy states of the confined electrons, sometimes called an artificial atom, are measured, and how the precision of these measurements depends on temperature. We also discuss the coupling of electrons inside the artificial atom to those in the leads of the SET, which results in the Kondo effect. We review measurements of the Kondo effect, which demonstrate that the Anderson Hamiltonian provides a quantitative description of the SET.

By using Ab initio approach, we have analysed Silicene-, Germanene- and Graphene-based molecular single-electron transistors. It is based on non-equilibrium greens function (NGEF) and density functional theory (DFT). Three different fullerene molecules are taken and optimization is done. In Coulomb blockade regime, silicene, germanene and graphene are kept above gate dielectric between drain and source for weak coupling. We have taken gold electrodes for SET environment. Gold is widely used as metal electrode in nanoscale devices. We have calculated the HOMO and LUMO values and total energy versus gate voltage. Charge stability diagrams are obtained by calculating charging energy as function of external gate potential. By these calculations, the analysis of three different molecular single-electron transistors is done. The total energies of these molecules are highly negative (very low) compared to other molecules.

Both experiments and theoretical studies have demonstrated that the interaction between the current carrying electrons and the induced polarization charge in single-molecule junctions leads to a strong renormalization of molecular charging energies. However, the effect on electronic excitations and molecular symmetries remain unclear. Using a theoretical framework developed for semiconductor nanostructure based single-electron transistors (SETs), we demonstrate that the image charge interaction breaks the molecular symmetries in a benzene based single-molecule transistor operating in the Coulomb blockade regime. This results in the appearance of a so-called blocking state, which gives rise to negative differential resistance (NDR). We show that the appearance of NDR and its magnitude in the symmetry-broken benzene SET depends in a complicated way on the interplay between the many-body matrix elements, the lead tunnel coupling asymmetry, and the bias polarity. In particular, the current reducing property of the blocking state causing the NDR, is shown to vanish under strongly asymmetric tunnel couplings, when the molecule is coupled stronger to the drain electrode. The calculated IV characteristic may serve as an indicator for image charge broken molecular symmetries in experimental situations.

Single electron transistors (SETs) has been proposed as a future basis for nanoelectric components. SETs, which utilize Coulomb blockade effect arising from the electrostatic charging energy of a single electron, are one of the promising candidates for future integrated circuits due to their extremely low power consumption and high-density integration. Here, we report on the study of the formation mechanism of a nanometer-scale Au chain on a patterned SiO 2 based wafer by controlling the reaction of raw materials to form citrate Au sol and aminosilane/dithiol treated SiO 2/ Si wafer. Three gold colloidal particles (~15 nm) were aligned in a chain to form a one-dimensional current path which was bridged on a 80 nm gap between source and drain metal electrode. The SET device exhibited a Coulomb blockade effect at 40 K.

We fabricate single electron transistors based on a single ZnO nanobelt using standard micro-fabrication techniques. The transport properties of the devices are characterized at room temperature and at low temperature (4.2 K). At room temperature, the source-drain current increases linearly as the bias voltage increases, indicating a good ohmic contact in the transistors. At 4.2 K, a Coulomb blockade regime is observed up to a bias voltage of a few millivolts. With scanning the back gate voltage, Coulomb oscillations can be clearly resolved with a period around 1 V. From the oscillations, the charging energy for the single electron transistor is calculated to be about 10 meV, which suggests that confined quantum dots exist with sizes around 35 nm in diameter. The irregular Coulomb diamonds are observed due to the multi-tunneling junctions between dots in the nanobelt.

A density functional theory (DFT)-based first principle approach has been employed to investigate the suitability of chlorobenzene-based single-electron transistor (SET) for the detection of few toxic gases such as hydrogen cyanide, arsine, and phosgene. The adsorption aspect of toxic gas molecules on the chlorobenzene with different orientations has been analyzed. The attributes such as charge density, molecular energy spectrum, density of states, and Mulliken population have been computed to scrutinize the effect of gas molecules on the surface of chlorobenzene. The sensing mechanism of adsorbate (toxic gases) with the adsorbent (chlorobenzene) has been authenticated in a single-electron transistor (SET) environment through total energy vs. gate voltage plot and charge stability diagram. The recovery time of the chlorobenzene-based SET gas sensor on the adsorption of HCN, AsH3, and COCl2 has been computed as 1.93ns, 0.45ns, and 36.31ns, respectively. Based on these findings, it is interesting to see that the COCl2 gas molecule shows strong physical adsorption with the most significant adsorption distance (3.629Å) with chlorobenzene, while AsH3-adsorbed chlorobenzene SET displays a low recovery time in comparison with other considered gases. The present analysis confirms a significantly better range of detection and improved recovery time using chlorobenzene-based single-electron transistor.

Recent modern fabrication technology allows us for the fabrication of nanometer-scaled devices, which is possible to observe single electronic or single electron tunneling phenomena (Averin & Likharev, 1991; Likharev, 1988; Likharev, 1999; Hanna et al., 1991; Tucker, 1992). On the other hand, MOSFET (metal-oxide-semiconductor field effect transistor) devices with channel length below 20 nanometer (nm) are no more properly operated because the downscaling of MOS devices causes a large statistical fluctuation of the threshold voltage. A possible approach to overcome this problem is to use the single electron devices for future VLSI (very large scale integrated circuit) (Takahashi et al., 1995; Saitoh et al., 2001). Nanometer scale single electron devices have the following features, i.e., low power consumption and small size. These are key features to realize ultra high density circuits. Single electron circuits with new architecture are also possible because the basic operation of single electron devices is quite different from that of conventional semiconductor devices. There are two major requirements for single electron tunneling phenomena (Coulomb blockade) to occur (Averin & Lhikarev, 1991; Likharev, 1988; Likharev, 1999). Firstly, thermal energy 倦喋劇 must be much smaller than elemental charging energy 結態 に系 ⁄ . This ensures that the transport of charges is in fact governed by the Coulomb charging energy. This condition can be fulfilled either by lowering the temperature or by decreasing the capacitance which means to reduce the island size. Usually, experiments are performed at temperatures of a few mK and for structures with island sizes of a few hundred nanometers. Second requirement is related to tunnel resistance which must exceed the quantum resistance (h ね結態 ⁄ ≈ は.の kΩ). This condition ensures that the wave functions of excess electrons between the barriers are basically localized. On the other word, in the case of lower tunnel resistance, excess charges extend over the barriers so that no single electron tunneling event can be possible. There are several types of circuits where the single electron tunneling phenomena are being explored, such as single electron box (Likharev, 1999), single electron transistor (SET) (Tucker, 1992; Takahashi et al., 1995; Saitoh et al., 2001; Wolf et al., 2010; Sun et al., 2011; Lee et al., 2009), single electron pump (Ono et al., 2003), single electron turnstile (Moraru et al., 2011) and single electron circuits with several junctions (1D and 2D arrays) (Nuryadi et al., 2003; Nuryadi et al., 2005). A double junction system is most important single electron circuit because of a basic component of SET. At small applied voltage, the system remains in the Coulomb blockade state, and no current flows through the double junctions. On the other hand, at higher applied

Novel medical applications involving embedded sensors, require ultra low energy dissipation with low-to-moderate performance (10kHz-100MHz) driving the conventional MOSFETs into sub-threshold operation regime. In this paper, we present an alternate ultra-low power computing architecture using Binary Decision Diagram based logic circuits implemented using Single Electron Transistors (SETs) operating in the Coulomb blockade regime with very low supply voltages. We evaluate the energy – performance tradeoff metrics of such BDD circuits using time domain Monte Carlo simulations and compare them with the energy-optimized CMOS logic circuits. Simulation results show that the proposed approach achieves better energy-delay characteristics than CMOS realizations.Keywordslow-energy circuitssingle electron transistorsbinary decision diagram logic circuits