scholarly journals Electromechanical Characteristics by a Vertical Flip of C70 Fullerene Prolate Spheroid in a Single-Electron Transistor: Hybrid Density Functional Methods

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2995
Author(s):  
Jong Woan Choi ◽  
Changhoon Lee ◽  
Eiji Osawa ◽  
Ji Young Lee ◽  
Jung Chul Sur ◽  
...  
Keyword(s):  
Density Functional ◽  
Electron Tunneling ◽  
Major Axis ◽  
Prolate Spheroid ◽  
Molecular Orbitals ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Gate Electrode ◽  
Axis Orientation ◽  
Hybrid Density Functional

In this study, the B3LYP hybrid density functional theory was used to investigate the electromechanical characteristics of C70 fullerene with and without point charges to model the effect of the surface of the gate electrode in a C70 single-electron transistor (SET). To understand electron tunneling through C70 fullerene species in a single-C70 transistor, descriptors of geometrical atomic structures and frontier molecular orbitals were analyzed. The findings regarding the node planes of the lowest unoccupied molecular orbitals (LUMOs) of C70 and both the highest occupied molecular orbitals (HOMOs) and the LUMO of the C70 anion suggest that electron tunneling of pristine C70 prolate spheroidal fullerene could be better in the major axis orientation when facing the gate electrode than in the major (longer) axis orientation when facing the Au source and drain electrodes. In addition, we explored the effect on the geometrical atomic structure of C70 by a single-electron addition, in which the maximum change for the distance between two carbon sites of C70 is 0.02 Å.

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

2013 ◽  
Vol 12 (06) ◽  
pp. 1350045 ◽  
Author(s):  
ANURAG SRIVASTAVA ◽  
BODDEPALLI SANTHIBHUSHAN ◽  
PANKAJ DOBWAL
Keyword(s):  
Coulomb Blockade ◽  
Density Functional ◽  
Stability Diagram ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Functional Theory ◽  
Charge Stability ◽  
Anthracene Molecule ◽  
The Stability ◽  
Experimental Values

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.

scholarly journals First-Principles Modeling of the Smallest Molecular Single Electron Transistor

2015 ◽  
Vol 2 (1) ◽  
pp. 33-39
Author(s):  
Mudassir M. Husain ◽  
Maneesh Kumar
Keyword(s):  
First Principles ◽  
Electron Tunneling ◽  
Energy Levels ◽  
Stability Diagram ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Discrete Energy ◽  
Weakly Coupled ◽  
Electron Transport Properties ◽  
Charging Energy

Using first-principles method the charging energy has been calculated; of the smallest single electron transistor (SET) consisting of only two carbon atoms while operating in coulumb blockade regime. The ethyne (C2H2) molecule is acting like a quantum dot (with discrete energy levels) and is weakly coupled to the gold electrodes (continuum). The quantum effects are significant and the conduction of current takes place through incoherent method via electron tunneling. The electronic levels of the molecule determine the electron transport properties. The molecule may be in several charged states from +2 to -2. It has been observed that the HOMO-LUMO gap is strongly reduced in solid state environment with metallic electrodes, as compared to the vacuum. This reduction is attributed to the image charges generated in the source and drain electrodes. This results in strong localization of charges in the molecule, a phenomenon addressed earlier. The charging energy has been calculated in vacuum and in SET environment. The interaction between molecule and the electrodes is treated self-consistently through Poisson equation. The charge stability diagram of the smallest molecular SET has been obtained.

A PSPICE Fast Model for the Single Electron Transistor

2019 ◽  
pp. 08-23
Author(s):  
Lobna Osman ◽  
Keyword(s):  
Low Power ◽  
Power Dissipation ◽  
High Speed ◽  
Electron Tunneling ◽  
Electronic Devices ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Electrical Characteristics ◽  
Nanoelectronic Devices ◽  
Low Power Dissipation

Motivated by the merits of low power dissipation, ultra-small size, and high speed of many nanoelectronic devices, They have been demonstrated to ensure future progress. Single-electron devices became one of the most important nanoelectronic devices due to their interesting electrical characteristics and behavior. Many research efforts moved to describe their electrical characteristics to use them with conventional electronic devices. This paper deals with modeling and simulation of such new electronic devices. This paper presents a model for the Single Electron Transistor (SET) and its application in simulating hybrid SET/MOS ADC and DAC converters. This model uses the orthodox theory of single-electron tunneling and determines the average current through the transistor. The proposed model is more flexible that is valid for a large range of drain to source voltage, valid for single or multi-gate SET and symmetric or asymmetric SET. Finally, using this model with MOSFET transistors to realize multi-bit Analog-to-Digital Converters (ADC) and Digital-to-Analog Converters (DAC). The hybrid n-bit DAC nano-circuits are simulated for (n=4 and 8) using Orcad Capture PSPICE. The performance of the SET/MOS hybrid n-bit ADC circuits were simulated (for n=3 and 8). The results show that the transient operation of hybrid SET/MOS circuit-based DAC could successfully operate at 1000K while ADC could operate at 144K. This performance can be compared with the pure SET circuits, the proposed converter circuits have been enhanced in the drive capability and the power dissipation. Compared with the other SET/MOS hybrid circuit, the implemented converter circuits have low simulation time, high speed, high load drivability, and low power dissipation.

GRAPHYNE-BASED SINGLE ELECTRON TRANSISTOR: AB INITIO ANALYSIS

NANO ◽  
2014 ◽  
Vol 09 (03) ◽  
pp. 1450032 ◽  
Author(s):  
J. V. N. SARMA ◽  
RAJIB CHOWDHURY ◽  
R. JAYAGANTHAN
Keyword(s):  
Coulomb Blockade ◽  
Density Functional ◽  
Stability Diagram ◽  
Single Electron ◽  
Present System ◽  
Single Electron Transistor ◽  
Poisson Equations ◽  
Charge Stability ◽  
Coulomb Blockade Regime ◽  
Charging Energy

The application of graphyne for a single-electron transistor (SET) that is operating in the Coulomb blockade regime is investigated in the first principles framework. Density functional theory modeling for graphyne has been used and the device environment has been described by a continuum model. The interaction between graphyne and the SET environment is treated with self-consistent Poisson equations. The charging energy as a function of gate voltage thus calculated has been used to obtain the charge stability diagram for the present system. The effect of electrode separation and the position of the molecule with respect to the dielectric on the gate coupling have been studied further. As compared with the previously studied systems on this line, graphyne has been observed to provide the gate coupling that is nearly close to that of benzene and graphene, but significantly greater than fullerene-based systems.

Quantum Current Modelling of Single Electron Transistors with N Potential Barrier

2019 ◽  
Vol 11 (12) ◽  
pp. 1261-1265
Author(s):  
Seyed Norollah Hedayat ◽  
Seyedeh Sahar Hedayat
Keyword(s):  
Electron Tunneling ◽  
Structural Parameters ◽  
Single Electron ◽  
Tunneling Effect ◽  
Single Electron Transistor ◽  
Single Electron Transistors ◽  
Current Voltage ◽  
Single Electron Tunneling ◽  
Quantum Current ◽  
New Type

The single electron transistor is a new type of switching device that uses controlled electron tunneling to amplify current. In this paper, we focus on some basic device characteristics like, single electron tunneling effect on which this single electron transistor works. In this research, transmission coefficient model of a single electron transistor with quantum dot arrays constraints is checked. Then, the current of the transistor is modeled on quantum dots. Finally, current–voltage characteristic based on quantum transport and structural parameters are analyzed.

scholarly journals Parallel Comparator based voltmeter using Single Electron Tunneling Transistor

2021 ◽  
pp. 251-266
Author(s):  
Anup Kumar Biswas
Keyword(s):  
Electron Tunneling ◽  
Block Diagram ◽  
Voltage Divider ◽  
Input Voltage ◽  
Single Electron ◽  
Small Range ◽  
Single Electron Transistor ◽  
Digital Output ◽  
In Series ◽  
Analog Voltage

By manipulating an electron that tunnels the tunnel junction of a single electron transistor, one will be able to reach a standard output logic “1” or logic “0”. The operation of the Single Electron Transistor (SET) is depending upon the bias voltage as well as the input signal(s). By varying the input voltage levels of a SET, the output voltage levels can significantly be changed on the basis of tunneling of an electron whether tunneling happened or not. As our concentration is the measuring of an unknown voltage, we are to implement a voltmeter system to provide a digital output of 3 bits whenever an unknown input voltage is kept in touching in the input terminal. A reference/standard voltage (say 8mV) will be connected in series with eight resistances ( 8 Rs) for the purpose of making a seven threshold voltages, for 7 comparators, in an ascending order of values from ground to reference voltage for seven comparators which are used in this present work. The voltmeter implemented consists of (i) a voltage divider, (ii) a set of seven comparators, (iii) seven Exclusive-OR gates and (iv) three 4-input OR gates. The concepts of implementing “Parallel Comparator based voltmeter” is discussed in two ways (i) by classical block diagram and (ii) using Single electron transistor based circuit. The measuring of an input analog voltage will not be the same as the digital output value. A 3-bit output indicates that the input analog voltage must lie on within a particular small range of voltage. The encoder circuit which is connected to the outputs of the comparators is hard to construct whenever the three terminals output are expressed with the output variables (Wi) of the comparators. For simple and user-friendly circuit, the outputs (Wi) of the comparators are modified to Di variables so as to get the same 3-bit encoder/voltmeter output. For this purpose, 7 extra component called 2-input XORs based on SET are used. Seven such XORs are set, and the output of them are passed to three 4-input OR gates according to the required logic expressions. It is found that all the output data of the voltmeter are coherently matched with the theoretical aspects. Processing delays are found out for all circuits. Power consumptions of all of them are shown in tabular and graphical forms. All the circuit we are intending to make are provided in due places with their logic circuit or simulation set and the simulation results are provided as well. Different truth tables are given for keeping track of whether input-output relationships matches with the theoretical results. We have thought of whether the present work circuits are faster or slower than the circuits of CMOS based-circuits. The power consumed at the time of tunneling event for a circuit is measured and sensed that it exists in the range between 1×10^(-18) Joules to 22×10^(-18)Joules which is very small amount. All the combinational circuits presented in this work are of SET-based.

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