News

Chemical route towards electronic devices in graphene

Essential electronic components, such as diodes and tunnel barriers, can be incorporated in single graphene wires (nanoribbons) with atomic precision.
Schematic of the synthesis procedure for the graphene nanoribbon heterostructures

 

Schematic of the synthesis procedure for the graphene nanoribbon heterostructures: Precursor molecules are converted through chemical synthesis into precisely controlled graphene nanoribbons. Image: Aalto University, Utrecht University and TU Delft.

The goal is to create graphene-based electronic devices with extremely fast operational speeds. The discovery was made in a collaboration between Aalto University and their colleagues at Utrecht University and TU Delft in the Netherlands. The work was published in Nature Communications.

The ‘wonder material’ graphene has many interesting characteristics, and researchers around the world are looking for new ways to utilise them. Graphene itself does not have the characteristics needed to switch electrical currents on and off and smart solutions must be found for this particular problem. “We can make graphene structures with atomic precision. By selecting certain precursor substances (molecules), we can code the structure of the electrical circuit with extreme accuracy,” explains Peter Liljeroth from Aalto University, who conceived the research project together with Ingmar Swart from Utrecht University.

Seamless integration

The electronic properties of graphene can be controlled by synthesizing it into very narrow strips (graphene nanoribbons). Previous research has shown that the ribbon’s electronic characteristics are dependent on its atomic width. A ribbon that is five atoms wide behaves similarly to a metallic wire with extremely good conduction characteristics, but adding two atoms makes the ribbon a semiconductor. “We are now able to seamlessly integrate five atom-wide ribbons with seven atom-wide ribbons. That gives you a metal-semiconductor junction, which is a basic building block of electronic components,” according to Ingmar Swart.

 

Metal-semiconductor-metal junction (tunnel barrier) incorporated into a single graphene nanoribbon: The atomic and electronic structure of the nanoribbons can be probed with atomic resolution using advanced microscopic techniques. Image: Aalto University, Utrecht University and TU Delft.

Chemistry on a surface

The researchers produced their electronic graphene structures through a chemical reaction. They evaporated the precursor molecules onto a gold crystal, where they react in a very controlled way to yield new chemical compounds. “This is a different method from that currently used to produce electrical nanostructures, such as those on computer chips. For graphene, it is so important that the structure is precise at the atomic level and it is likely that the chemical route is the only effective method," Ingmar Swart concludes.

Electronic characteristics

The researchers used advanced microscopic techniques to also determine the electronic and transport characteristics of the resulting structures. It was possible to measure electrical current through a graphene nanoribbon device with an exactly known atomic structure. “This is the first time where we can create e.g. a tunnel barrier and really know its exact atomic structure. Simultaneous measurement of electrical current through the device allows us to compare theory and experiment on a very quantitative level,” says Peter Liljeroth.

This research was funded by the Academy of Finland, the European Research Council and NWO (The Netherlands Organisation for Scientific Research) Graduate Programme.

Journal reference:

P.H. Jacobse, A. Kimouche, T. Gebraad, M.M. Ervasti, J.M. Thijssen, P. Liljeroth and I. Swart, Electronic components embedded in a single graphene nanoribbon, Nature Communications, doi: 10.1038/s41467-017-00195-2.

Link to the artice (nature.com)

Further information:

Professor Peter Liljeroth
Tel: +358 50 363 6115
[email protected]
http://physics.aalto.fi/groups/stm/

  • Published:
  • Updated:
Share
URL copied!

Related news

Heikko kirkastuma, kuva: Metsähovin radiotutkimusasema
Press releases Published:

New study: The quiet Sun is much more active than we thought

The quiet Sun has been studied considerably less than the active Sun.
Pohjoisen ikirouta-alueen vehreää kasvillisuutta. Kuva: Ive van Krunkelsven
Press releases, Research & Art Published:

Greenhouse gas emissions from permafrost area larger than earlier estimated

Plant roots in soil stimulate microbial decomposition, a mechanism called the priming effect. A recent study published in Nature Geoscience shows that the priming effect alone can cause emission of 40 billion tonnes carbon from permafrost by 2100.
vaping
Press releases, Research & Art Published:

How vaping companies exploit Instagram for youth-oriented marketing?

Researchers use artificial intelligence to analyse hundreds of thousands of Instagram posts about vaping
Kuvituskuva: Matti Ahlgren.
Press releases Published:

Fast communications and flexibility helped grocery retailers cope with the coronavirus in spring

Research shows that daily communications, flexible planning and resourcing, and agility in action were important for helping the grocery trade get through the first wave of the coronavirus.