scholarly journals Temperature Dependence of Electrical Characteristics of Carbon Nanotube Field-Effect Transistors: A Quantum Simulation Study

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ali Naderi ◽  
S. Mohammad Noorbakhsh ◽  
Hossein Elahipanah
Keyword(s):  
Carbon Nanotube ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Quantum Simulation ◽  
Subthreshold Swing ◽  
Short Channel ◽  
Principal Characteristics ◽  
Channel Effects ◽  
Consistent Solution ◽  
Drain Conductance

By developing a two-dimensional (2D) full quantum simulation, the attributes of carbon nanotube field-effect transistors (CNTFETs) in different temperatures have been comprehensively investigated. Simulations have been performed by employing the self-consistent solution of 2D Poisson-Schrödinger equations within the nonequilibrium Green's function (NEGF) formalism. Principal characteristics of CNTFETs such as current capability, drain conductance, transconductance, and subthreshold swing (SS) have been investigated. Simulation results present that as temperature raises from 250 to 500 K, the drain conductance and on-current of the CNTFET improved; meanwhile the on-/off-current ratio deteriorated due to faster growth in off-current. Also the effects of temperature on short channel effects (SCEs) such as drain-induced barrier lowering (DIBL) and threshold voltage roll-off have been studied. Results show that the subthreshold swing and DIBL parameters are almost linearly correlated, so the degradation of these parameters has the same origin and can be perfectly influenced by the temperature.

Numerical study of carbon nanotube field effect transistors in presence of carbon–carbon third nearest neighbor interactions

2014 ◽  
Vol 28 (24) ◽  
pp. 1450167 ◽  
Author(s):  
Ali Naderi
Keyword(s):  
Carbon Nanotube ◽  
Field Effect ◽  
Nearest Neighbor ◽  
Field Effect Transistors ◽  
Numerical Study ◽  
Tight Binding ◽  
Hamiltonian Matrix ◽  
Short Channel ◽  
Channel Effects ◽  
Consistent Solution

In this paper, for the first time, we have used a more precise Hamiltonian matrix based on first nearest neighbor (1NN) and third nearest neighbor (3NN) carbon–carbon interactions to simulate carbon nanotube field effect transistors (CNTFETs). By taking the interactions with more distant neighbors into account, an improvement in tight-binding picture is gained. A self-consistent solution of Schrodinger equation based on nonequilibrium Green's function (NEGF) formalism coupled to a two-dimensional Poisson's equation for treating the electrostatics of the device has been employed to simulate CNTFETs. A tight-binding Hamiltonian with an atomistic (pz orbitals) mode space basis in the ballistic limits has been used to describe the carbon nanotube (CNT) region. Simulations show that in the presence of 3NN, the energy bandgap of the CNT decreases and consequently the simulated device has lower threshold voltage compared to a simulated device with just 1NN. Short channel effects study demonstrates that neglecting 3NN underestimates the subthreshold swing and overestimates ON/OFF current ratio. All these investigations show that for simulating a CNTFET more precisely, the 3NN interactions can be taken into account in addition to the 1NN.

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.

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 DESIGN OPTIMIZATION OF EXTREMELY SHORT-CHANNEL GRADED SI/SIGE HETEROJUNCTION TUNNEL FIELD-EFFECT TRANSISTORS FOR LOW POWER APPLICATIONS

2018 ◽  
Vol 51 (6) ◽  
pp. 757
Author(s):  
Nguyen Dang Chien
Keyword(s):  
Design Optimization ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Subthreshold Swing ◽  
Short Channel Effects ◽  
Short Channel ◽  
Channel Effects ◽  
Low Threshold ◽  
Standby Power ◽  
Dimensional Simulation

This study investigates, by a two-dimensional simulation, the design optimization of a proposed 8 nm tunnel field-effect transistor (TFET) for low standby power (LSTP) applications utilizing graded Si/SiGe heterojunction with device parameters based on the ITRS specifications. The source Ge mole fraction should be designed approximately 0.8 because using lower Ge fractions causes severe short-channel effects while with higher values does not significantly improve the device performance but may create big difficulties in fabrication. Based on simultaneously optimizing the subthreshold swing, on- and off-currents, optimum values of source doping, drain doping and length of the proposed device are approximately 1020 cm-3,                1018 cm-3, and 10 nm, respectively. The 8 nm graded Si/SiGe TFET with optimized device parameters demonstrates high on-current of 360 μA/μm, low off-current of 0.5 pA/μm, low threshold voltage of 85 mV and very steep subthreshold swing of sub-10 mV/decade. The designed TFET with graded Si/SiGe heterojunction exhibits an excellent performance and makes it an attractive candidate for future LSTP technologies because of its reality to be fabricated with existing FET and SiGe growth techniques.

Comparative Performance Analysis of Nanowire and Nanotube Field Effect Transistors

2021 ◽  
pp. 54-70
Author(s):  
Raj Kumar ◽  
Shashi Bala ◽  
Arvind Kumar
Keyword(s):  
Performance Analysis ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Ballistic Transport ◽  
High Mobility ◽  
Short Channel Effects ◽  
Short Channel ◽  
Comparative Performance ◽  
Channel Effects ◽  
And Performance

To have enhanced drive current and diminish short channel effects, planer MOS transistors have migrated from single-gate devices to three-dimensional multi-gate MOSFETs. The gate-all-around nanowire field-effect transistor (GAA NWFET) and nanotube or double gate-all-around field-effect transistors (DGGA-NTFET) have been proposed to deal with short channel effects and performance relates issues. Nanowire and nanotube-based field-effect transistors can be considered as leading candidates for nanoscale devices due to their superior electrostatic controllability, and ballistic transport properties. In this work, the performance of GAA NWFETs and DGAA-NT FETs will be analyzed and compared. III-V semiconductor materials as a channel will also be employed due to their high mobility over silicon. Performance analysis of junctionless nanowire and nanotube FETs will also be compared and presented.

Analysis of short-channel effects in organic field-effect transistors

2005 ◽  
Author(s):  
Joshua N. Haddock ◽  
Xiaohong Zhang ◽  
Shijun Zheng ◽  
Seth R. Marder ◽  
Bernard Kippelen
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Short Channel Effects ◽  
Organic Field Effect Transistors ◽  
Short Channel ◽  
Channel Effects
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