A New Approach to the Characteristics and Short-Channel Effects of Double-Gate Carbon Nanotube Field-Effect Transistors using MATLAB: A Numerical Study

2012 ◽  
Vol 67 (6-7) ◽  
pp. 317-326 ◽  
Author(s):  
Alireza Heidari ◽  
Niloofar Heidari ◽  
Foad Khademi Jahromi ◽  
Roozbeh Amiri ◽  
Mohammadali Ghorbani
Keyword(s):  
Carbon Nanotube ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Open Boundary ◽  
Double Gate ◽  
Short Channel Effects ◽  
Drain Voltage ◽  
Short Channel ◽  
Channel Effects ◽  
The Impact

In this paper, first, the impact of different gate arrangements on the short-channel effects of carbon nanotube field-effect transistors with doped source and drain with the self-consistent solution of the three-dimensional Poisson equation and the Schr¨odinger equation with open boundary conditions, within the non-equilibrium Green function, is investigated. The results indicate that the double-gate structure possesses a quasi-ideal subthreshold oscillation and an acceptable decrease in the drain induced barrier even for a relatively thick gate oxide (5 nm). Afterward, the electrical characteristics of the double-gate carbon nanotube field-effect transistors (DG-CNTFET) are investigated. The results demonstrate that an increase in diameter and density of the nanotubes in the DG-CNTFET increases the on-state current. Also, as the drain voltage increases, the off-state current of the DG-CNTFET decreases. In addition, regarding the negative gate voltages, for a high drain voltage, increasing in the drain current due to band-to-band tunnelling requires a larger negative gate voltage, and for a low drain voltage, resonant states appear

scholarly journals Analyses of Short Channel Effects of Single-Gate and Double-Gate Graphene Nanoribbon Field Effect Transistors

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Hojjatollah Sarvari ◽  
Amir Hossein Ghayour ◽  
Zhi Chen ◽  
Rahim Ghayour
Keyword(s):  
Threshold Voltage ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Tight Binding ◽  
Graphene Nanoribbon ◽  
Basis Set ◽  
Double Gate ◽  
Short Channel Effects ◽  
Short Channel ◽  
Channel Effects

Short channel effects of single-gate and double-gate graphene nanoribbon field effect transistors (GNRFETs) are studied based on the atomistic pz orbital model for the Hamiltonian of graphene nanoribbon using the nonequilibrium Green’s function formalism. A tight-binding Hamiltonian with an atomistic pz orbital basis set is used to describe the atomistic details in the channel of the GNRFETs. We have investigated the vital short channel effect parameters such as Ion and Ioff, the threshold voltage, the subthreshold swing, and the drain induced barrier lowering versus the channel length and oxide thickness of the GNRFETs in detail. The gate capacitance and the transconductance of both devices are also computed in order to calculate the intrinsic cut-off frequency and switching delay of GNRFETs. Furthermore, the effects of doping of the channel on the threshold voltage and the frequency response of the double-gate GNRFET are discussed. We have shown that the single-gate GNRFET suffers more from short channel effects if compared with those of the double-gate structure; however, both devices have nearly the same cut-off frequency in the range of terahertz. This work provides a collection of data comparing different features of short channel effects of the single gate with those of the double gate GNRFETs. The results give a very good insight into the devices and are very useful for their digital applications.

SDC-CNTFET: STEPWISE DOPING CHANNEL DESIGN IN CARBON NANOTUBE FIELD EFFECT TRANSISTORS FOR IMPROVING SHORT CHANNEL EFFECTS IMMUNITY

2014 ◽  
Vol 28 (07) ◽  
pp. 1450048 ◽  
Author(s):  
ZAHRA JAMALABADI ◽  
PARVIZ KESHAVARZI ◽  
ALI NADERI
Keyword(s):  
Carbon Nanotube ◽  
Impurity Concentration ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Doping Profile ◽  
Short Channel Effects ◽  
Device Structure ◽  
Short Channel ◽  
Channel Effects ◽  
Consistent Solution

A novel carbon nanotube field-effect transistor with stepwise doping profile channel (SDC-CNTFET) is introduced for short-channel effects (SCEs) improvement. In SDC-CNTFET, the channel is divided into five sections of equal length. Impurity concentration was reduced from 0.8 nm-1 to zero from the source side to the drain side of the channel, with stepwise profile. The devices have been simulated by the self-consistent solution of two-dimensional (2D) Poisson–Schrödinger equations, within the nonequilibrium Green's function (NEGF) formalism. We demonstrate that the proposed structure for CNTFETs shows considerable improvement in device performance focusing on leakage current and ON–OFF current ratio. In addition, the investigation of SCEs for the proposed structure shows the improved drain-induced barrier lowering (DIBL) and subthreshold swing (SS). Moreover, we will prove that the proposed structure has acceptable performance at different values of channel impurity concentration in terms of delay and power-delay product (PDP). All these investigations introduce SDC-CNTFET as a more reliable device structure in short-channel regime.

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