Enhanced high-frequency performance of top-gated graphene FETs due to substrate-induced improvements in charge carrier saturation velocity
Artikel i vetenskaplig tidskrift, 2021

High-frequency performance of top-gated graphene field-effect transistors (GFETs) depends to a large extent on the saturation velocity of the charge car-riers, a velocity limited by inelastic scattering by surface optical phonons from the dielectrics surrounding the chan-nel. In this work, we show that by simply changing the graphene channel surrounding dielectric with a material having higher optical phonon energy, one could improve the transit frequency and maximum frequency of oscillation of GFETs. We fabricated GFETs on conventional SiO2/Si substrates by adding a thin Al2O3 interfacial buffer layer on top of SiO2/Si substrates, a material with about 30% higher optical phonon energy than that of SiO2, and compared performance with that of GFETs fabricated without adding the interfacial layer. From S-parameter measurements, a transit frequency and a maximum frequency of oscillation of 43 GHz and 46 GHz, respectively, were obtained for GFETs on Al2O3 with 0.5 µm gate length. These values are approximately 30% higher than those for state-of-the-art GFETs of the same gate length on SiO2. For relating the improvement of GFET high-frequency performance to improvements in the charge carrier saturation velocity, we used standard methods to extract the charge carrier veloc-ity from the channel transit time. A comparison between two sets of GFETs with and without the interfacial Al2O3 layer showed that the charge carrier saturation velocity had increased to 2·10^7 cm/s from 1.5·10^7 cm/s.

graphene

maximum frequency of oscillation

Field-effect transistors (FETs)

transit frequency

optical phonons

saturation velocity

Författare

Muhammad Asad

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

Kjell Jeppson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

Andrei Vorobiev

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

Marlene Bonmann

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

Jan Stake

Chalmers, Mikroteknologi och nanovetenskap (MC2), Terahertz- och millimetervågsteknik

IEEE Transactions on Electron Devices

0018-9383 (ISSN)

Vol. 68 2 899-902

Kolbaserat höghastighet 3D GaN elektroniksystem

Stiftelsen för Strategisk forskning (SSF), 2014-03-01 -- 2019-06-30.

Graphene Core Project 3 (Graphene Flagship)

Europeiska kommissionen (EU), 2020-04-01 -- 2023-03-31.

Flexibla terahertz detektorer i grafen

Vetenskapsrådet (VR), 2018-01-01 -- 2021-12-31.

Styrkeområden

Informations- och kommunikationsteknik

Nanovetenskap och nanoteknik (SO 2010-2017, EI 2018-)

Infrastruktur

Kollberglaboratoriet

Nanotekniklaboratoriet

Ämneskategorier

Elektroteknik och elektronik

Nanoteknik

Annan elektroteknik och elektronik

DOI

10.1109/TED.2020.3046172

Mer information

Senast uppdaterat

2021-03-10