2026-09-14T06:23:52Zhttps://gredos.usal.es/oai/requestoai:gredos.usal.es:10366/1406772025-06-05T12:40:28Zcom_10366_143088com_10366_123103com_10366_3823com_10366_4756com_10366_4746com_10366_4101com_10366_4055com_10366_3946col_10366_143117col_10366_68518col_10366_4109
Gestión del Repositorio Documental de la Universidad de Salamanca
advisor
Meziani, Yahya Moubarak
advisor
Velázquez Pérez, Jesús Enrique
author
Delgado Notario, Juan Antonio
2020-01-24T09:27:40Z
2020-01-24T09:27:40Z
2019
http://hdl.handle.net/10366/140677
10.14201/gredos.140677
[EN] This Thesis focuses on the study of the response to Terahertz (THz) electromagnetic
radiation of different silicon substrate-compatible FETs. Strained-Si MODFETs, state-of-
the-art FinFETs and graphene-FETs were studied.
The first part of this thesis is devoted to present the results of an experimental and
theoretical study of strained-Si MODFETs. These transistors are built by epitaxy of
relaxed-SiGe on a conventional Si wafer to permit the fabrication of a strained-Si electron
channel to obtain a high-mobility electron gas. Room temperature detection under
excitation of 0.15 and 0.3 THz as well as sensitivity to the polarization of incoming
radiations were demonstrated. A two-dimensional hydrodynamic-model was developed to
conduct TCAD simulations to understand and predict the response of the transistors. Both
experimental data and TCAD results were in good agreement demonstrating both the
potential of TCAD as a tool for the design of future new THz devices and the excellent
performance of strained-Si MODFETs as THz detectors (75 V/W and 0.06 nW/Hz0.5).
The second part of the Thesis reports on an experimental study on the THz behavior of
modern silicon FinFETs at room temperature. Silicon FinFETs were characterized in the
frequency range 0.14-0.44 THz. The results obtained in this study show the potential of
these devices as THz detectors in terms of their excellent Responsivity and NEP figures
(0.66 kV/W and 0.05 nW/Hz0.5).
Finally, a large part of the Thesis is devoted to the fabrication and characterization of
Graphene-based FETs. A novel transfer technique and an in-house-developed setup were
implemented in the Nanotechnology Clean Room of the USAL and described in detail in
this Thesis. The newly developed transfer technique enables to encapsulate a graphene
layer between two flakes of h-BN. Raman measurements confirmed the quality of the
fabricated graphene heterostructures and, thus, the excellent properties of encapsulated
graphene. The asymmetric dual grating gate graphene FET (ADGG-GFET) concept was
introduced as an efficient way to improve the graphene response to THz radiation. High
quality ADGG-GFETs were fabricated and characterized under THz radiation. DC
measurements confirmed the high quality of graphene heterostructures as it was shown
on Raman measurements. A clear THz detection was found for both 0.15 THz and 0.3
THz at 4K when the device was voltage biased either using the back or the top gate of the
G-FET. Room temperature THz detection was demonstrated at 0.3 THz using the
ADGG-GFET. The device shows a Responsivity and NEP around 2.2 mA/W and 0.04
nW/Hz0.5 respectively at respectively at 4K.
It was demonstrated the practical use of the studied devices for inspection of hidden
objects by using the in-house developed THz imaging system.
eng
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
THz
Plasma-waves
FETs
MODFETs
FinFETs
Silicon
Graphene
Electrónica
Transporte de electrones
Fotoelectricidad
Silicon- and Graphene-based FETs for THz technology
info:eu-repo/semantics/doctoralThesis
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URL
https://gredos.usal.es/bitstream/10366/140677/1/DFA_TesisDoctoralJADelgadoNotario_SiliconGrapheneFetsTHZ.pdf
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DFA_TesisDoctoralJADelgadoNotario_SiliconGrapheneFetsTHZ.pdf
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https://gredos.usal.es/bitstream/10366/140677/6/DFA_TesisDoctoralJADelgadoNotario_SiliconGrapheneFetsTHZ.pdf.txt
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DFA_TesisDoctoralJADelgadoNotario_SiliconGrapheneFetsTHZ.pdf.txt