Molecular Doping of Epigraphene for Device Applications
Doctoral thesis, 2020

Epitaxial graphene grown on silicon carbide, or epigraphene, offers in principle a suitable platform for electronic applications of graphene which require scalable, reproducible, and high-quality material. However, one of the main drawbacks of epigraphene lies in the difficulty in controlling its carrier density, which hinders its usefulness in future applications.

To solve this problem, this thesis introduces a novel molecular doping method which utilizes acceptor molecules mixed with a polymer. This combination results in a dopant blend that is simple to apply onto epigraphene, and capable of providing controllable, potent, and homogeneous doping over large areas. This technique opens many different avenues for potential applications, three of which are explored in this work.

The doping method was successfully used to create practical graphene quantum resistance standards, based on the quantum Hall effect. It was confirmed by two independent metrology institutes that epigraphene meets the stringent criteria for use in precision measurements of resistance.

Doped epigraphene was also used to develop magnetic field sensors. These Hall sensors were shown to rival and even surpass the best graphene-based Hall sensors reported in literature thus far, including record-low magnetic field detection limits at room temperature. These Hall sensors also demonstrated promising performance at high temperatures, with the potential to one day outmatch industrial sensors in the automotive and military temperature ranges.

Lastly, doped epigraphene was used to create a proof-of-concept terahertz detector. The devices demonstrated highly sensitive and wide-band coherent detection of terahertz signals, with record-low power consumption requirements. It was found that an optimized device could potentially allow for the creation of detector arrays that can provide quantum limited detection across the entire terahertz range, and revolutionize sensors used in next-generation space telescopes.

Molecular Doping

Graphene

epitaxial graphene

THz

Metrology

Hall Effect

Kollektorn, Kemivägen 9
Opponent: Prof. Sophie Guéron, Laboratoire de Physique des Solides Orsay, Université Paris Sud, France

Author

Hans He

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Epitaxial graphene grown on silicon carbide, or epigraphene, offers in principle a suitable platform for electronic applications of graphene which require scalable, reproducible, and high-quality material. However, one of the main drawbacks of epigraphene lies in the difficulty in controlling its carrier density, which hinders its usefulness in future applications.

To solve this problem, this thesis introduces a novel molecular doping method which utilizes acceptor molecules mixed with a polymer. This combination results in a dopant blend that is simple to apply onto epigraphene, and capable of providing controllable, potent, and homogeneous doping over large areas. This technique opens many different avenues for potential applications, three of which are explored in this work.

The doping method was successfully used to create practical graphene quantum resistance standards, which meet the stringent criteria for use in precision measurements of resistance.

Doped epigraphene was also used to develop magnetic field sensors, which rival and even surpass the best graphene-based Hall sensors reported in literature thus far. These Hall sensors also demonstrated promising performance at high temperatures, with the potential to one day outmatch industrial sensors.

Lastly, doped epigraphene was used to create a proof-of-concept terahertz detector. It was found that an optimized device could potentially allow for the creation of detector arrays that can provide ultra-sensitive detection across the entire terahertz range, and revolutionize sensors used in next-generation space telescopes.

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Production

Materials Science

Roots

Basic sciences

Driving Forces

Innovation and entrepreneurship

Infrastructure

Nanofabrication Laboratory

Subject Categories

Signal Processing

Other Electrical Engineering, Electronic Engineering, Information Engineering

Condensed Matter Physics

ISBN

978-91-7905-309-3

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4776

Publisher

Chalmers University of Technology

Kollektorn, Kemivägen 9

Online

Opponent: Prof. Sophie Guéron, Laboratoire de Physique des Solides Orsay, Université Paris Sud, France

More information

Latest update

6/10/2020