Carbon Nanotube Transistors: A Review

2015

In this paper we have focused on the carbon nano tube field effect transistor technology. The advantages of CNTFET over MOS technology are also discussed. The structure and types of CNTFET are given in detail along with the variation of threshold voltage with respect to the alteration in CNT diameter. The characteristics curve between gate to source current and drain to source voltage is plotted. Various fixed and variable parameters of CNT are also focused.

CSVTU Research Journal on Engineering and Technology

As Silicon industry is evolving it is scaling down day by day. With the reduced size of the transistor, the craving for high performance devices has also taken place. For MOSFET, with very small channel length size reduction is limited and below certain dimensions the device will undergo uncontrolled and unpredictable leakage current, parasitic capacitances and power dissipation issues. Hence, researchers have implemented a novel device to overcome the above-mentioned issues called as CNTFET (Carbon NanoTube Field Effect Transistor). CNTFET provides high carrier mobility, reduced delay and power consumption, better noise margin, suitable contact resistance and fast switching speed. In this review paper, different CNTFET structures and classifications, chiral vector and chirality have been discussed in detail.

2013

An overview of the different types of CNTFET which have large potential to semiconductor industry and microelectronic systems is presented. The present paper is focused on the structure of the various types of CNTFET and their technology characteristics depending on the specific CNT used: single-walled or

2020

Presently, the low power and high efficiency are imperishable problem in technological gadgets. With the emergence of technologies like 5G and others, it has become requisite to meet the challenge before peeved. In this paper we entrust FinFETs, and CNTFETs technologies which are found to be upbeat field of research. The paper presents the performance enhancements of CNTFETs at 14 nm node and discusses the important areas of their applications and future scope.

Carbon Nano Tube Field Effect Transistor (CNTFET) has various extraordinary electrical and mechanical properties and due to this CNTFET is turning out to be the forefront material for future electronics. In this paper, the review of CNTFETs is presented. MOSFET technology has limited scope for further enhancement. With a motivation to find alternatives, we explore the domain of CNTFETs. The structure, operation and the various performance parameters have been discussed. The effect of threshold voltage, temperature, channel length,delay and power consumption for both CNTFETs and MOSFET devices have been discussed. Previous studies show that CNTFETs are far better than MOSFET device. It is propsed as an alternative to MOSFET because of its promising features. However, challenges faced by CNTFETs have been discussed.

International Journal of High Speed Electronics and Systems, 2006

This paper discusses the device physics of carbon nanotube field-effect transistors (CNTFETs). After reviewing the status of device technology, we use results of our numerical simulations to discuss the physics of CNTFETs emphasizing the similarities and differences with traditional FETs. The discussion shows that our understanding of CNTFET device physics has matured to the point where experiments can be explained and device designs optimized. The paper concludes with some thoughts on challenges and opportunities for CNTFET electronics.

This paper discusses a comprehensive analytical study of electrical properties of sin-gle‐wall conventional carbon nanotube field‐effect transistor (CNTFET) devices of subthreshold swing (SS), transconductance (g m), and extension resistance. The analytical expressions for SS and g m have been derived based on channel modulated potential. In the study, it was observed that SS value of the CNTFET device is equal to 60 mV/decade, which is smaller than the conventional and double gate metal‐ oxide‐semiconductor field‐effect transistors. The subthreshold swing degrades at larger tube's diameter and gate‐source voltage due to increased source‐drain leakage current. Carbon nanotube field‐effect transistor devices achieve larger g m at large gate‐source voltage, which has a disadvantage of reducing the allowable voltage swing at the drain. The extension resistance of the device falls with diameter of the tube. The subthreshold swing (SS) is the important parameter to sustain the scaling of silicon transistor because leakage power is strongly influenced by SS of the device. Subthreshold swing value indicates the minimum gate‐source voltage (V gs) required to lower the subthreshold current by a factor of 10. Steep SS devices are of great interest due to demand of power and energy‐efficient digital circuits. As metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) scaled below 45 nm, the subthreshold leakage current becomes more significant due to short‐channel effects (SCEs), parameter variations, 1-3 and strong coupling between temperature and subthreshold leakage current. 4,5 The fundamental thermodynamic limit on the minimum operational voltage and switching energy of the conventional FETs is ideally 60 mV/decade at room temperature, but in practice , the gate oxide screens the gate fields and the coupling between the gate and channel is not perfect, which causes SS to be larger than the ideal value. 6-10 The carbon nanotube FET (CNTFET) is a promising candidate for future electron devices, and rapid progress in this field has made it possible to fabricate CNTFET‐based integrated circuits. In facts, CNTFET is the substitute of silicon MOS due to excellent control of SCEs 11-13 as well as physical and electrical properties. 14,15 Although the SS of the CNTFET device has been reported theoretically by researchers, 16-18 this parameter has not been discussed in detail compared with the other parameters. In nanotube junctions, the parasitic resistance (R P) is given as the sum of contact resistance (R C) and the extension resistance (R ext). The R ext contributes more in the R P than in the R C. Lower R ext improves the intrinsic performance of the device. 19 In the literature, less attention has been given on the study of R ext compared with R C. 20 In this paper, we studied the SS and R ext of CNTFET after using our previously derived drain current equation. 15 The SS is close to 60 mV/decade at room temperature in CNTFET device. We have also observed that the SS of the CNTFET device is

Microelectronics Journal, 2009

For the first time, we present a scaling study of carbon nanotube field-effect transistors (CNTFETs) using a two-dimensional model. We investigate the scaling issues in device performance focusing on transconductance characteristics, output characteristics, average velocity, I on /I off ratio, subthreshold swing and drain-induced barrier lowering (DIBL) with different gate oxide thicknesses and carbon nanotube (CNT) diameters. We concluded that the I on /I off ratio increases with the gate oxide thickness reduction and increase in the CNT diameter and lead to a high on-state current. Furthermore, leakage current reduces with decrease in the gate oxide thickness, but it becomes higher in CNTFETs with larger CNT diameter. Also, our results show the output conductance, transconductance, voltage gain and average electron velocity at the top of the barrier improve in CNTFETs with thinner gate oxide and larger CNT diameter. In addition, the investigation of short channel effects shows that CNTFETs with thinner gate oxide offer lower DIBL and subthreshold swing, but in the CNTFETs with larger CNT diameter DIBL and subthreshold swing become worse.

irjtas.com, 2018

Carbon Nano-tube field impact Transistors (CNTFET) are guaranteeing nano-scaled gadgets to actualizing helter skelter execution really thick and low energy circuits. An carbon Nano-tube field impact transistor alludes will An fet that uses An absolute CNT alternately an show from claiming CNT"s Concerning illustration the channel material As opposed to greater part silicon in the accepted MOSFET structure. Those center of a CNTFET will be a carbon nano-tube. In this paper, the Audit for CNTFETs will be exhibited. Those structure, operation and the qualities for diverse sorts of CNTFET"s need been examined. Those operation, dc qualities for CNTFETs have been exhibited what"s more dissection of the execution of Different aspects. With those decrease from claiming capability should enhance the MOSFET innovation in the next decade or so, there will be a surge to attempt will Figure a supplanting. Carbon nano-tubes, which would sheets for grapheme rolled up, would being investigated concerning illustration displacements to silicon units. This new population for transistors, known as carbon nano-tube transistors, may be a standout amongst those current heading adrift advances to displace MOSFETs. Notwithstanding those enormous Growth and progress, there need aid even now troublesome issues that requirement with be fathomed. Therefore, on assistance with the research, this paper surveys every last one of current Look into that need been finished Also layouts what's to come Examine that is necessary should make extensive scale VLSI chip using carbon nano-tube transistors.

… Journal of Electronic Engineering Research, ISSN

As the scaling of Si MOSFET approaches towards its limiting value, new alternatives are coming up to overcome these limitations. In this paper first we have reviewed carbon nanotube field effect transistor (CNTFET) and types of CNTFET. We have then studied the effect of channel length and chirality on the drain current for planer CNTFET. The I d~Vd curves for planer CNTFETs having different channel lengths and diameters are plotted. For the same, I d~Vd curves for different applied gate voltages are also plotted. We have then discussed the effect of diameter on the characteristic curves for a cylindrical CNTFET. Finally a brief comparison between the performance of Si-MOSFET and CNTFET is given.