Modeling and Simulation Graphene based Nano FET : A Review

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 10 Issue: 08 | Aug 2023 www.irjet.net p-ISSN: 2395-0072
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Modeling and Simulation Graphene based Nano FET : A Review
1Neha, 2Manoj Kumar
1Research Scholar, ECE Department, Om Sterling Global University, Hisar, Haryana (India)
2Associate professor, ECE Department, Om Sterling Global University, Hisar, Haryana (India)
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Abstract: Graphene-based Field Effect Transistor
modelling is described in this article. Utilizing SILVACO
TCAD tools, modelling is completed. The structure is built
using the virtual ATLAS framework, and the model is used
to assess the efficacy of graphene-based FETs. To create
the device structure, we first deposit a 5nm thick
polysilicon layer rather than a graphene sheet. As the
channel material, graphene is used, and it is modelled as a
semiconductor with a 10,000 cm 2 /V-s carrier mobility.
The output characteristic and transfer curve are plotted as
characteristic curves with TONYPLOT. There is no band
gap in pure graphene. As a result, it is regarded as a zero
bandgap or semi-metal semiconductor. Because GFETs
lack a bandgap and have a lower I ON/I OFF ratio than
silicon-based transistors, they are still less efficient for use
in digital logic circuits than Si transistors. Due to its
extreme mobility, it is better suited for RF applications.
Thus, in this article, it is possible to get the maximum
cutoff frequency (f T) and the maximum oscillation
frequency (f max), which are thought to represent the
FOMs of RF transistors.
Keywords: Graphene, grapheme based FET, GFET,
Modelling
1. INTRODUCTION
Planar, two-dimensional, and just one layer thick,
graphene is a crystallized form of carbon. It is a key
component of fullerenes, carbon nanotubes, charcoal, and
one of carbon-graphite's most significant allotropes. In
order to generate extended benzene ring configurations,
graphene is made up of sp2 hybridized carbon atoms. With
a measured electron mobility of up to 250,000 cm2 V 1 s 1
(suspended form), graphene is known to possess
exceptional electrical characteristics as a result of its
structure. Additionally, graphene has been shown to have
remarkable mechanical qualities and to have the greatest
breaking strengths ever measured (42 N-m-1).
Additionally, graphene has great optical qualities, which
allow it to be used in optical devices like light detectors.
[1].
The structure's single atom of thickness is formed by a
honeycomb lattice of carbon atoms, two-dimensional
structure known as graphene. In-depth analyses of each
aspect of this unique substance have been sparked by its
recent experimental discovery [2].
Figure 1: The Composition of a Graphene Layer
Graphene, which has been researched for a very long time
and is often referred to as "2D graphite," is used most
frequently to illustrate the characteristics of various
carbon-based materials. There are many ways in which the
fundamental GFET, a three-terminal device, resembles the
conventional FET. It consists of a drain, a supply, and a
high or back gate. The supply and drain metal electrodes of
a GFET are separated from one another by a narrow
graphene channel, which is typically tens of microns thick,
unlike a silicon-based junction transistor [3].The gate
regulates the behaviour of the channel by dictating how
electrons react. For the GFET, there are three major gate
configurations. As indicated below, typical transistors will
either have a high gate, a world back gate, or both.

Figure: 2 Proposed Structure of GFET
A GFET's gate regulates the flow of electrons or holes
across its channel, much like the gate in vintage
semiconductor FETs. The extraordinary sensitivity of the
graphene FETs is due to the fact that all of this flows on the
surface of the junction transistor channel, which is just one
atom thick. In semiconductor devices, current typically
moves via electrons or holes. The GFET, however, allows
for equal conductivity between electrons and holes. When
a hole carrier is conducting in the channel region under a
negative bias, GFET devices behave in a usual ambipolar
manner. On the other hand, a positive bias causes lepton
carrier conductivity[4].
Figure: 3 The various nanomaterial-based FET
technologies for the detection of biomarkers are shown
schematically in the image above.
One such dual gate G-FET implementation is shown in Fig.
3. Figure 3(a) displays the 2-dimensional read, and Figure
3(b) displays the matching three-dimensional read. The
graphene channel is desired in this arrangement between
two gate chemical compound layers, namely between the
high gate and the rear gate chemical compound (substrate)
layers [5]. The SiO2 serves as the rear gate's insulator. The
rear gate, or Si wafer, creates a very inexpensive layer. By
depositing on a thick SiO2 layer, which was afterwards
generated to develop on a heavily doped back gate that is
that the Si wafer, the bilayer graphene channel is desired.
Channel inversion must often be worn down in order for a
G-FET to function as a switch that switches between the
ON and OFF states by applying the proper back gate bias
voltage. The supply and drain resistance of the GFET are
controlled by rear gate.
Figure 4: a) 2D view of dual gate GFET b) 3D viewof a twin
gate GFET
2. RELATED WORK
2.1 Some of the recent related works are given below
The integrated graphene-based FET (GFET) biosensors at
the nanoscale are the main topics of this study. Given how
quickly it may spread from one person to another in only
minutes, the new kind of coronavirus has clearly emerged
as a severe problem in today's dynamic environment.
Compared to other coronaviruses like SARS and MERS,
COVID-19 may spread more quickly. Due to its
resemblance in form under the electron microscope, the
term corona is obtain from the Latin word definition
"crown." In order to emphasize this roadmap, some of the
most current works are examined and examined for this
goal. [6].
Its potential uses have generated a great deal of attention
due to the exceptional electrical characteristics as well as
good optical, mechanical, and thermodynamic qualities.

The utility of large area graphene as a channel material in
MOSFETs has been constrained by its zero band gap. In
addition to outlining a few techniques researchers have
used to produce band gaps in graphene, this study also
covers the fundamental physics of graphene. Along with a
model for the current and charge densities in top gated
Large Area Graphene FETs, a few graphene
implementations in FETs and their findings are also
provided. [7].
Now is the time to seriously consider finding alternatives
to silicon for use in transistors. In the modern world, if
Gordon Moore's forecast is to come true, the
semiconductor industry will soon enter a post-silicon era.
Nanomaterials generated from graphene are now being
considered as potential post-silicon electronics device
materials. Field effect behaviour in graphene and graphite-
based devices is the main topic of this work, which also
studies and analyzes it. Additionally, it gives a brief
overview of graphene's theoretical characteristics before
going through its properties as they relate to electrical
devices and looking at how they affect the functionality of
transistors made of graphene in both logic and
radiofrequency applications. It is possible to draw the
conclusion that graphene's outstanding mobility may not
be its most enticing property from a device standpoint,
contrary to what is often believed. Instead, GFFT may be
able to overcome the unfavourable short-channel effects
that restrict their performance by being scaled to shorter
channel lengths and greater speeds if devices with very
thin channels are developed.. [8].
In the last ten years, the study of graphene and its use in
cutting-edge electronics has grown quickly. Post-silicon
technology is increasingly necessary for industry as
Moore's law starts to plateau. Additionally, terahertz
detectors and receivers cannot be implemented using
current technology, which are necessary for a variety of
applications, including as security scanning and medical
imaging. Due to its exceptional electronic properties,
including observed electronic mobilities of up to 2 105
cm2 V1 s1 in suspended graphene samples, graphene is
regarded as a key potential candidate for replacing silicon
in current CMOS technology as well as realizing field effect
transistors for terahertz detection. In relation to the
implementation of graphene transistors, this article
examines the physics and electrical characteristics of
graphene[9]. Mechanical exfoliation, chemical vapour
deposition, and epitaxial growth are a few common
methods used to create graphene. Since graphene has a
zero bandgap and is semi-metallic, this poses a problem
for digital electronics applications and is one of the
difficulties in fabricating graphene transistors.
Consequently, the research also discusses several
techniques for opening a bandgap in graphene employing
bilayer graphene and graphene nanoribbons. Key merit
metrics used in the literature are extracted, and the
fundamental workings of a typical field effect transistor
are described. The overview of certain cutting-edge
graphene field effect transistor examples is offered at the
end, with a special emphasis on monolayer, bilayer, and
graphene nanoribbons.[10].
This study provides a thorough overview of current
advancements in graphene field effect transistors, taking
into account a variety of factors including manufacturing,
modelling and simulation tools, and applications,
particularly in sensors, outlining the directions for the
future. Due to silicon's limits in terms of shrinking
transistor size, various alternative materials for
manufacturing have been tested in order to comply with
Moore's law and enhance the transistor density of an
integrated circuit due to qualities like increased carrier
mobility and very high trans-conductance gain, among
others, one such material, graphene, demonstrates its
suitability as a silicon substitute. Additionally, high-speed
analogue VLSI, RF, and biosensor circuits are finding that
G-FET is the best alternative. [11].
3. NEED OF GRAPHENE-BASED FET
GFET Challenges
For silicon-based transistors, graphene FETs are a
beautiful substitute. However, there are a number of
difficulties that make industrial production difficult,
including the following:
1) Bandgap limitations
2) Fabrication prices
3) Saturation
Benefits of Graphene-Based FETs
Low resistance losses and greater cooling than
semiconductors are the results of graphene's improved
electrical and thermal conductivity. As a result, graphene
transistors might provide improved performance and
potency[12].
The entire channel is on the surface because the
structure is only one atom thick. Thus, in detector
applications, the channel is wide open to the material or
surroundings underneath the look at. This makes some
GFETs sensitive and appropriate for a variety of bio- and
chemical-sensing applications[13]. For instance, it might
pick up on a molecule sticking to or detaching from a
surface. Not to mention, research has indicated that

employing a thin, top-gate dielectric material improves
GFET properties like open-circuit gain, forward
transmission constant, and cutoff frequency. This opens up
the possibility of using GFETs in a variety of applications
and for very high-frequency operations [14]. Theoretically,
the junction transistor can change far more quickly than
silicon-based FETs, approaching the rate of change at very
high rates. Standard semiconductor materials' lattice
structure has various restrictions that make it heat-
dissipate rapidly at higher frequencies. On the other hand,
the high lepton quality, polygonal form lattice structure,
and other features change it to operate at the rate
frequencies much better.
4. MODELING & SIMULATION
Programme for G-FET modelling and simulation. This
section compares a few of the widely available modelling
and analytical tools for G-FET. GFET tool, which simulates
conducting behavioural research on the electrical and
thermal properties of a GFET. The G-FET's voltage and
current can be calculated using this device while the G-
FET's temperature is kept constant[16]. The tools for this
inquiry employ a drifting technique and a prolixity system.
The following research projects on GFETs may also be
estimated and started using this method, i.e.
a) Carrier viscosity
b) Temperature profile studies
c) Drift haste and
d) Electric field studies
When creating the models for ATLAS simulator (a device
simulator for 2D and 3D structures), Silvaco, a CAD
programme, is utilised. This simulator aids in simulating
the study of the electronic circuits' electric, optical, and
thermal properties. It is simple to understand how the
gadget operates thanks to these simulation studies.
Theses, which are created using emulsion accessories such
as double, ternary, and quaternary, assist in creating an
accurate calculation of the bias[17].
Meter The enormous signal GFET for ambi-polar graphene
high frequency electronic circuits is modelled using the
virtuoso spectre circuit simulator tool. In processes like
the multiplier phase sensor, radio frequency sub
harmonious mixer, and frequency doppelgänger, this large
signal model is frequently used. For RF operations, there is
a particular Virtuso spectre interpretation. The tool, called
Virtuoso Spectre RF, can be used to assess the DC and AC
characteristics, the RC birth for detention estimate, and the
electromagnetic (EM) analysis of GFET grounded
circuits[18].
Sentaurus is a well-known EDA tool for simulating the
Graphene FET grounded detectors used in the detection of
single beachfront DNA (also known as ssDNA) and
reciprocal DNA (also known as cDNA) (10). It is a cutting-
edge design and optimisation tool for GFET grounded
circuits. This may aid in creating device simulations in
several dimensions. The simulation may include a study of
the physical properties of electric, optical, or thermal
systems. Electronic biases of the semiconductor grounded
or combinational kind are also possible[19].
5. APPLICATIONS OF GRAPHENE
 Due to its remarkable properties, graphene may
be employed in a broad variety of applications.
Here are a few potential uses for graphene:
 RF circuits (because to the high mobility values
reported in it) and significant cutoff frequencies in
graphene field-effect transistors (for instance, Lin
et al.'s study showed that graphene nanoribbon-
based FETs had cutoff frequencies of 100 GHz).
Any of the aforementioned techniques may be
used to customize a band gap in logic circuits.
 Since graphene is more transparent and flexible
than the less transparent and more brittle indium
tin oxide that is currently employed in the
industry, it may be used to build transparent
electrodes for solar technology.
 Due to its semi-metallic behaviour with high
mobility and strong flexibility[20], interconnect
applications.
 Graphene may one day be utilized to make
supercapacitors because of its high surface area to
volume ratio.
6. CONCLUSION
The operate of graphene in logic circuits is presently not
practical due to low on/off current levels. Due to its high
mobility and high cutoff frequency, it may be employed in
RC circuits, but the issue of large off currents still exists
and resulting in much greater power dissipation than the
existing, highly low powered CMOS technology. Further
study may enable the creation of bandgaps in graphene
without significantly reducing mobility, resulting in the
creation of graphene FETs with a favourable on/off
current ratio and great mobility. So, in the next years,
graphene may replace other materials as the primary
component of electrical gadgets.

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Modeling and Simulation Graphene based Nano FET : A Review