556 research outputs found
Modelling of field-effect transistors based on 2D materials targeting high-frequency applications
New technologies are necessary for the unprecedented expansion of
connectivity and communications in the modern technological society. The
specific needs of wireless communication systems in 5G and beyond, as well as
devices for the future deployment of Internet of Things has caused that the
International Technology Roadmap for Semiconductors, which is the strategic
planning document of the semiconductor industry, considered since 2011,
graphene and related materials (GRMs) as promising candidates for the future of
electronics. Graphene, a one-atom-thick of carbon, is a promising material for
high-frequency applications due to its intrinsic superior carrier mobility and
very high saturation velocity. These exceptional carrier transport properties
suggest that GRM-based field-effect transistors could potentially outperform
other technologies.
This thesis presents a body of work on the modelling, performance prediction
and simulation of GRM-based field-effect transistors and circuits. The main
goal of this work is to provide models and tools to ease the following issues:
(i) gaining technological control of single layer and bilayer graphene devices
and, more generally, devices based on 2D materials, (ii) assessment of
radio-frequency (RF) performance and microwave stability, (iii) benchmarking
against other existing technologies, (iv) providing guidance for device and
circuit design, (v) simulation of circuits formed by GRM-based transistors.Comment: Thesis, 164 pages, http://hdl.handle.net/10803/40531
Effect of Device Variables on Surface Potential and Threshold Voltage in DG-GNRFET
In this paper we present four simple analytical threshold voltage model for short- channel and length of saturation velocity region (LVSR) effect that takes into account the built – in potential of the source and drain channel junction, the surface potential and the surface electric field effect on double – gate graphene nanoribbon transistors. Four established models for surface potential, lateral electric field, LVSR and threshold voltage are presented. These models are based on the easy analytical solution of the two dimensional potential distribution in the graphene and Poisson equation which can be used to obtain surface potential, lateral electric field, LVSR and threshold voltage. These models give a closed form solution of the surface potential and electrical field distribution as a function of structural parameters and drain bias. Most of analytical outcomes are shown to correlate with outcomes acquired by Matlab simulation and the end model applicability to the published silicon base devices is demonstrated
Analytical model of 1D Carbon-based Schottky-Barrier Transistors
Nanotransistors typically operate in far-from-equilibrium (FFE) conditions,
that cannot be described neither by drift-diffusion, nor by purely ballistic
models. In carbonbased nanotransistors, source and drain contacts are often
characterized by the formation of Schottky Barriers (SBs), with strong
influence on transport. Here we present a model for onedimensional field-effect
transistors (FETs), taking into account on equal footing both SB contacts and
FFE transport regime. Intermediate transport is introduced within the Buttiker
probe approach to dissipative transport, in which a non-ballistic transistor is
seen as a suitable series of individually ballistic channels. Our model permits
the study of the interplay of SBs and ambipolar FFE transport, and in
particular of the transition between SB-limited and dissipation-limited
transport
Engineering interband tunneling in nanowires with diamond cubic or zincblende crystalline structure based on atomistic modeling
We present an investigation in the device parameter space of band-to-band
tunneling in nanowires with a diamond cubic or zincblende crystalline
structure. Results are obtained from quantum transport simulations based on
Non-Equilibrium Green's functions with a tight-binding atomistic Hamiltonian.
Interband tunneling is extremely sensitive to the longitudinal electric field,
to the nanowire cross section, through the gap, and to the material. We have
derived an approximate analytical expression for the transmission probability
based on WKB theory and on a proper choice of the effective interband tunneling
mass, which shows good agreement with results from atomistic quantum
simulation.Comment: 4 pages, 3 figures. Final version, published in IEEE Trans.
Nanotechnol. It differs from the previous arXiv version for the title and for
some changes in the text and in the reference
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