CHARGE STABILITY AND CONDUCTANCE ANALYSIS OF ANTHRACENE-BASED SINGLE ELECTRON TRANSISTOR

Low power consumption, small device size and better controlled onto the charge carriers are the factors, that made Single-electron transistor (SET) a suitable candidate for molecular electronics; yet there are some improvements that can be done in order to use it practically. The single electron transistor (SET) operates through the tunnelling of electron via two tunnel junctions. Choosing a suitable island material plays a key role in the tunnelling of electron through the tunnel junctions. In the present work, the First principle calculations of carbon-nanotube and boron-nanotube based Single-Electron Transistors have been performed. The three types of configurations of nanotubes i.e. zigzag (5,0), armchair (3,3) and chiral (4,2), of the smallest possible diameter (approximately 4A ),have been used. The calculations have been carried out using Atomistic toolkit (ATK-VNL) simulation package which is a density functional theory (DFT) based package. In the present work, local density approximations (LDA) as well as generalized gradient approximation(GGA) have been used to demonstrate the properties of nanotubes-based SET. These approaches have been implemented for a nanotube that is lying just above the gate dielectric. On the either side of the dielectric the electrodes are present, source in the left and drain in the right. The metallic electrodes made of gold (W=5.28eV) and the dielectric material of the dielectric constant have been used. The charging energies and additional energies of both types of nanotubes-based SET in the isolated as well as in the electrostatic environment have been calculated using the approximations. The calculated values of the charging energies in the electrostatic environment have been found to be less than the charging energies in isolated configuration that shows the renormalization of molecular energy levels. Variations of total energies against gate voltages and Charge stability diagrams (CSD) have been discussed.

The present paper discusses charge stability and conductance analyses of benzene- and zigzag graphene fragment-based single-electron transistors (SETs) operating in the Coulomb blockade regime. Graphene and benzene are modeled using density functional theory-based ab initio analyses, treating the interaction between graphene/benzene and the SET environment self-consistently. The devices consist of an oriented graphene/benzene island coupled with source and drain electrodes. The charging energy as a function of the external gate potential has been analyzed to verify the dependence of the charge stability and conductance of the oriented SETs on the source/drain bias and gate potential. Comparative analysis of these models shows that the SET with vertically oriented graphene is more stable and has better conductance in comparison with the benzene-based SET.

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.

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.

In this paper, we propose and implement a single-electron transistor (SET) based on cobalt oxide for the first time. The SETs were fabricated through nanofabrication process compatible with the CMOS technology. A cobalt oxide (Co1-yO) on the surface of the source (S) and drain (D) Co electrodes is utilized to act as a quantum dot (QD). The diameter of QD is calculated to be 2.3 nm. The interface between Co1-yO and Co thin films (S/D electrodes) is used as tunneling junctions. The SET based on CoO exhibits typical single electron transport characteristics. Owing to the high Coulomb blockade energy (~180 meV), the Coulomb blockade regions still remain at room temperature (300 K), revealing the nanometer scale CoO-based SETs have great potential to operate at room temperature.

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

Modeling and analysis of energy quantization effects on single electron inverter performance

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

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.

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

Ferromagnetic single electron transistor

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.

Single-electron transistors are fabricated with a planar self-aligned process using chemical mechanical polishing. The method is demonstrated with Ti∕TiOx junctions and resistless lithography. The device characterization showed Coulomb blockade up to 433K. High temperature data allowed one to calculate the impact of the process variations on the charging energy and thus on a realistic operating temperature. It is found that single electron devices can have an operating temperature range similar to conventional silicon transistors, opening the door to hybrid designs. These approaches are promising because advanced functionality is created by an optimal combination of both technology strengths.

The single-electron transistor (SET) is a prime candidate for reading out the final state of a qubit in a solid-state quantum computer. Such a measurement requires the detection of subelectron charge motion in the presence of random charging events. We present a detection scheme where the signals from two SETs are cross-correlated to suppress unwanted artifacts due to charge noise. This technique is demonstrated by using the two SETs to detect the charge state of two coupled metal dots, thereby simulating charge transfer and readout in a two-qubit system. These measurements indicate that for comparable buried dopant semiconductor architectures, the minimum measurement time required to distinguish between the two charge states is of the order of 10 ns.

First-principles study of MoS2, phosphorene and graphene based single electron transistor for gas sensing applications