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Characterisation and Modelling of Graphene FETs for Terahertz Mixers and Detectors

Michael Andersson (Institutionen för mikroteknologi och nanovetenskap, Terahertz- och millimetervågsteknik )
Göteborg : Chalmers University of Technology, 2016. ISBN: 978-91-7597-453-8.- 92 s.
[Doktorsavhandling]

Graphene is a two-dimensional sheet of carbon atoms with numerous envisaged applications owing to its exciting properties. In particular, ultrahigh-speed graphene field effect transistors (GFETs) are possible due to the unprecedented carrier velocities in ideal graphene. Thus, GFETs may potentially advance the current upper operation frequency limit of RF electronics. In this thesis, the practical viability of high-frequency GFETs based on large-area graphene from chemical vapour deposition (CVD) is investigated. Device-level GFET model parameters are extracted to identify performance bottlenecks. Passive mixer and power detector terahertz circuits operating above the present active GFET transit time limit are demonstrated. The first device-level microwave noise characterisation of a CVD GFET is presented. This allows for the de-embedding of the noise parameters and construction of noise models for the intrinsic device. The correlation of the gate and drain noise in the PRC model is comparable to that of Si MOSFETs. This indicates higher long-term GFET noise relative to HEMTs. An analytical power detector model derived using Volterra analysis on the FET large-signal model is verified at frequencies up to 67 GHz. The drain current derivatives, intrinsic capacitors and parasitic resistors of the closed-form expressions for the noise equivalent power (NEP) are extracted from DC and S-parameter measurements. The model shows that a short gate length and a bandgap in the channel are required for optimal FET sensitivity. A power detector integrated with a split bow-tie antenna on a Si substrate demonstrates an optical NEP of 500 pW/Hz^1/2 at 600 GHz. This represents a state-of-the-art result for quasi-optically coupled, rectifying direct detectors based on GFETs operating at room temperature. The subharmonic GFET mixer utilising the electron-hole symmetry in graphene is scaled to operate with a centre frequency of 200 GHz, the highest frequency reported so far for graphene integrated circuits. The down-converter circuit is implemented in a coplanar waveguide (CPW) on Si and exhibits a conversion loss (CL) of 29 ± 2 dB in the 185-210 GHz band. In conclusion, the CVD GFETs in this thesis are unlikely to reach the performance required for high-end RF applications. Instead, they currently appear more likely to compete in niche applications such as flexible electronics.

Nyckelord: Field-effect transistors (FETs), graphene, integrated circuits, microwave amplifiers, millimetre and submillimetre waves, nanofabrication, noise modelling, nonlinear device modelling, power detectors, subharmonic resistive mixers, terahertz detectors, Volterra



Denna post skapades 2016-08-26. Senast ändrad 2016-12-05.
CPL Pubid: 240834

 

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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Terahertz- och millimetervågsteknik

Ämnesområden

Informations- och kommunikationsteknik
Nanovetenskap och nanoteknik
Elektroteknik
Nanoteknik

Chalmers infrastruktur

NFL/Myfab (Nanofabrication Laboratory)
National Laboratory in Terahertz Characterisation

Relaterade publikationer

Inkluderade delarbeten:


10 dB small-signal graphene FET amplifier


Resistive Graphene FET Subharmonic Mixers: Noise and Linearity Assessment


Microwave characterization of Ti/Au-graphene contacts


Microwave noise characterization of graphene field effect transistors


Antenna-integrated 0.6 THz FET direct detectors based on CVD graphene


Effect of ferroelectric substrate on carrier mobility in graphene field-effect transistors


An Accurate Empirical Model Based on Volterra Series for FET Power Detectors


Feasibility of Ambient RF Energy Harvesting for Self-Sustainable M2M Communications Using Transparent and Flexible Graphene Antennas


A 185-215-GHz Subharmonic Resistive Graphene FET Integrated Mixer on Silicon


Examination

Datum: 2016-09-23
Tid: 10:00
Lokal: Kollektorn (A423), MC2, Kemivägen 9, Chalmers
Opponent: Prof. Henri Happy, Institute of Electronic, Microelectronic and Nanotechnology, University of Lille 1: Sciences and Technologies, France

Ingår i serie

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie 4134


Technical report MC2 - Department of Microtechnology and Nanoscience, Chalmers University of Technology MC2-342