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3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
POTENTIAL AND DRAIN CURRENT SIMULATION
OF A SYMMETRIC DOUBLE GATED MOLYBDENUM
DISULFIDE (MOS2) TRANSISTOR
R. Sridevi
Assistant Professor, Department of Electronics and Communication Engineering,
M.Kumarasamy College of Engineering, Karur (India).
E-mail: sridevir.ece@mkce.ac.in
ORCID: https://orcid.org/0000-0003-300-3336
J. Charles Pravin
Associate Professor, Centre for VLSI Design, Department of Electronics and Communication,
Kalasalingam Academy of Research and Education. Virudhunagar (India).
E-mail: charles@klu.ac.in
ORCID: https://orcid.org/0000-0002-9009-6274
Recepción: 28/11/2019 Aceptación: 04/12/2020 Publicación: 30/11/2021
Citación sugerida:
Sridevi, R., y Pravin, J. C. (2021). Potential and drain current simulation of a symmetric double gated
Molybdenum Disulde (MoS2) transistor. 3C Tecnología. Glosas de innovación aplicadas a la pyme, Edición
Especial, (noviembre, 2021), 385-395. https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
386 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
ABSTRACT
As the scaling of silicon MOSFET reaches its physical limit, research eorts have been
made in exploring alternative devices. In this paper, we have examined the enhanced drain
current, electrostatic potential, mobility, and electric eld for a symmetric structure of
Double gated Molybdenum Disulde (MoS2) transistor. The performance of the device has
been simulated using Technology Computer-Aided Design (TCAD) simulation tool. The
above mentioned comparison model of drain current built by use of symmetric Double
gated MoS2 transistor has shown superior performances when compared with that of
Silicon transistor. There is an enhancement of 0.1 µA in its drain current and the mobility
is 50 higher than the silicon based transistor, under the condition that this device has the
same geometry. It was performed by incorporating the quantum mechanical eects in
molybdenum disulde (MoS2) based transistor. Due to its high performance in low power
operating voltages, MoS2 transistor will be suitable for low power applications.
KEYWORDS
2D material, MoS2, Drain Current, FET, TCAD Simulation tool.
387 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
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1. INTRODUCTION
In the recent decade, silicon-based transistor has reached its scaling limit. Hence, researchers
have been discovering solutions for nding alternative channel materials for future
semiconductor devices; such has the transition metal dichalcogenides (TMDs) material of
MoS2, which is chosen due to their high ON- OFF ratio and mobility. Unlike graphene,
MoS2 material has large bandgap of 1.23 eV, so it can be easily turned o. Compared
to Silicon dioxide, high k dielectric materials are mostly preferred because of its reduced
threshold voltage and improve current ON/OFF ratio (Ajayan et al., 2017; Pravin et al.,
2016a; Ryu et al., 2016; Boucart & Ionescu, 2007).
We present the simulated result of drain current, electrostatic potential, mobility, and
electric eld for symmetric double gated MoS2 transistor using Technology Computer-
Aided Design (TCAD) simulation tool. Here we have been used the drift diusion model
is the carrier transport model in Sentaurus Device (“Sentaurus™ Device User Guide.
Version K-2015.06”, 2015). Based on the literature survey (Pravin et al., 2016b; Pravin et
al., 2018; Semiconductor Industry Association, 2015; Tiwari et al., 2017), our numerical
model has been simulated. Finally, we have to extract the physical parameters of drain
current, electrostatic potential, mobility, and electric eld for MoS2 based transistor by
TCAD simulation tool. We have to compare the obtained results of MoS2 material and
silicon material, where our proposed model has shown the higher performance.
In this paper, we address a symmetric Double gated MoS2 transistor, it produces the higher
drain current compared to Single gate MoS2 transistor.
2. MATERIALS AND METHODS
The physical structure of symmetric Double gated MoS2 based transistor is presented in
Figure 1, which has been modeled with channel length (Lch) of 20 nm, 10 nm thickness of
the gate oxide (tox), and channel thickness (tch) of 10 nm (Jiang et al., 2015). These values
are shown in Table 1.
388 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Figure 1. Device geometry of symmetric Double gated MoS2 transistor.
Source: own elaboration.
Table 1. Values of the physical structure of the double-gate MoS2-based symmetric transistor.
Parameters Values
Channel Length 20 nm
Gate Oxide 10 nm
Channel thickness 10 nm
Drain/Source Doping 1e18
Channel Doping 1e21
MoS2 band gap 1.23 eV
Source: own elaboration.
The Drift diusion model and Shockley Read Hall Recombination model have been used
in the simulation for determine the drain current of proposed device (“Sentaurus™ Device
User Guide. Version K-2015.06”, 2015).
DRIFT-DIFFUSION MODEL:
In Sentaurus Device, the default carrier transport model of drift-diusion model is used.
The electron current density and hole current density are given below,
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3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Due to spatial variations of the electron anity, the electrostatic potential and the band gap.
These terms are taken into the report the contribution. The remaining terms of eective
masses of mn and mp are taken into the report the contribution due to the spatial variation
and the gradient of concentration.
By using Einstein relation, the diusivities Dn and Dp are derived through the mobilities.
SCHOCKLEY-READ-HALL RECOMBINATION:
In Sentaurus Device, Schockley-Read-Hall (SRH) recombination model is achieved:
The dierence between the detect level and intrinsic level is termed as Etrap.
SRH DOPING DEPENDENCE:
In Sentaurus Device, the doping dependence of the SRH lifetimes is modeled with the help
of Scharfetter relation:
When the argument Doping Dependence is particularized for the SRH Recombination,
where the Scharfetter relation is used.
390 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
3. RESULTS
Based on the equations obtained for Drift-Diusion model and Schockley-Read-Hall
Recombination was carried out in the MoS2 structure for nding the drain current,
electrostatic potential, mobility, and electric eld.
The nal results show that the proposed MoS2 device structure displayed improved
performances in terms of both drain current as well as mobility than the silicon transistor.
3.1. SIMULATION RESULT OF DRAIN CURRENT
The MoS2 channel material based transistor device is simulated with drift diusion model
in Sentaurus Device. Figure 2 depicts the analyzation of the drain current of the transistor
device. The obtained result produces higher drain current at 1 V of gate voltage for short
channel length device. This result illustrates that the MoS2 material produces higher drain
current compared to silicon material. When we are applied high gate voltages it reaches the
high drain current.
Figure 2. Comparison of drain current for MoS2 material and Silicon material.
Source: own elaboration.
391 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Figure 3. Comparison of drain current for MoS2 material and Silicon material.
Source: own elaboration.
Figure 3 shows the output characteristics of drain current for MoS2 material and silicon
material. This result depicts the drain current with the function of gate voltage at 1 V of
drain voltage.
3.2. SIMULATION RESULT OF ELECTRIC FIELD
Figure 4. Analyzation of electric eld for MoS2 material and Silicon material.
Source: own elaboration.
Figure 4 shows the electric eld for MoS2 material and silicon material. This result depicts
the electric eld for MoS2 produces a higher value tan the silicon transistor.
392 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
3.3. SIMULATION RESULT OF MOBILITY
Figure 5. Mobility for MoS2 material and Silicon material.
Source: own elaboration.
3.4. SIMULATION RESULT OF POTENTIAL
Figure 6. Comparison of electrostatic potential for MoS2 material and Silicon material.
Source: own elaboration.
The above gure shows the mobility, and electrostatic potential for a symmetric structure
of double gated MoS2 transistor. The heavy doping of body makes dicult the potential
calculation. To overcome this constraint, using Poisson equation in existence of important
body doping. The electrostatic potential is achieved by solving Poisson equation.
393 https://doi.org/10.17993/3ctecno.2021.specialissue8.385-395
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
4. CONCLUSIONS
This paper introduced a MoS2 based transistor with high k dielectric material, which has
merits in terms of device performance of the reduced threshold voltage. A performance
evaluation was done for the MoS2 based transistor for nding out the drain current,
electrostatic potential, mobility, and electric eld. The performance of the device has been
simulated using Technology Computer-Aided Design (TCAD) simulation tool. The above
mentioned comparison model of drain current built by use of symmetric Double gated
MoS2 transistor has shown superior performances when compared with that of Silicon
transistor. There is an enhancement of 0.1 µA in its drain current and the mobility is
50 higher than the silicon based transistor, under the condition that this device has the
same geometry. It was performed by incorporating the quantum mechanical eects in
molybdenum disulde (MoS2) based transistor. We have successfully investigated the MoS2
material based transistor and its characteristics.
ACKNOWLEDGEMENT
The authors are grateful to centre for VLSI Design, Department of Electronics and
Communication Engineering, Kalasalingam Academy of Research and Education (KARE)
for supporting this research.
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Noviembre 2021
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