A promising route to the scalable production of highly crystalline graphene films

August 25, 2016

Researchers discovered a procedure to restore defective graphene oxide structures that cause the material to display low carrier mobility. By applying a high-temperature reduction treatment in an ethanol environment, defective structures were restored, leading to the formation of a highly crystalline graphene film with excellent band-like transport. These findings are expected to come into use in scalable production techniques of highly crystalline graphene films.

Graphene is a material with excellent electric conductivity, mechanical strength, chemical stability, and a large surface area. Its structure consists of a one-atom-thick layer of carbon atoms. Due to its positive attributes, research on its synthesis and application to electronic devices is being conducted around the world. While it is possible to create graphene from graphene oxide (GO), a material produced by chemical exfoliation from graphite through oxidative treatment, this treatment causes defective structures and the existence of oxygen-containing groups, causing GO to display low conducting properties. So far, carrier mobility, the basic indicator with which transistor performance is expressed, remained at a few cm2/Vs at most. A group of researchers led by Ryota Negishi, assistant professor, and Yoshihiro Kobayashi, professor, Graduate School of Engineering, Osaka University; Masashi Akabori, associate professor, Japan Advanced Institute of Science and Technology; Takahiro Ito, associate professor, Graduate School of Engineering, Nagoya University; and Yoshio Watanabe, Vice Director, Aichi Synchrotron Radiation Center, have developed a reduction treatment through which the crystallinity of GO was drastically improved.

The researchers coated a substrate with 1-3 extremely thin layers of GO and added a small amount of ethanol to the up to 1100°C high temperature reduction process. The addition of the carbon-based ethanol gas led to the effective restoration of the defective graphene structure. For the first time in the world, this group managed to observe a band-like transport reflecting the intrinsic electric transport properties in chemically reduced GO films. Band-like transport is a conduction mechanism in which the carriers use the periodic electric mechanisms in solid crystals as a transmission wave. The observed band transport in this study achieved a carrier mobility of ~210 cm2/Vs, currently the highest level observed in chemically reduced GO films.

The successful creation of thin graphene films achieved through the above reduction method has opened up the possibility of their application in a diverse set of electronic devices and sensors. The findings of this research group form a milestone in the development of scalable materials that utilize graphene's excellent physical properties.

This research was featured in Scientific Reports (Nature Publishing Group) on July 1, 2016.

Osaka University

Related Graphene Articles from Brightsurf:

How to stack graphene up to four layers
IBS research team reports a novel method to grow multi-layered, single-crystalline graphene with a selected stacking order in a wafer scale.

Graphene-Adsorbate van der Waals bonding memory inspires 'smart' graphene sensors
Electric field modulation of the graphene-adsorbate interaction induces unique van der Waals (vdW) bonding which were previously assumed to be randomized by thermal energy after the electric field is turned off.

Graphene: It is all about the toppings
The way graphene interacts with other materials depends on how these materials are brought into contact with the graphene.

Discovery of graphene switch
Researchers at Japan Advanced Institute of Science and Technology (JAIST) successfully developed the special in-situ transmission electron microscope technique to measure the current-voltage curve of graphene nanoribbon (GNR) with observing the edge structure and found that the electrical conductance of narrow GNRs with a zigzag edge structure abruptly increased above the critical bias voltage, indicating that which they are expected to be applied to switching devices, which are the smallest in the world.

New 'brick' for nanotechnology: Graphene Nanomesh
Researchers at Japan advanced institute of science and technology (JAIST) successfully fabricated suspended graphene nanomesh (GNM) by using the focused helium ion beam technology.

Flatter graphene, faster electrons
Scientists from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel developed a technique to flatten corrugations in graphene layers.

Graphene Flagship publishes handbook of graphene manufacturing
The EU-funded research project Graphene Flagship has published a comprehensive guide explaining how to produce and process graphene and related materials (GRMs).

How to induce magnetism in graphene
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechani-cal, electronic and optical properties.

Graphene: The more you bend it, the softer it gets
New research by engineers at the University of Illinois combines atomic-scale experimentation with computer modeling to determine how much energy it takes to bend multilayer graphene -- a question that has eluded scientists since graphene was first isolated.

How do you know it's perfect graphene?
Scientists at the US Department of Energy's Ames Laboratory have discovered an indicator that reliably demonstrates a sample's high quality, and it was one that was hiding in plain sight for decades.

Read More: Graphene News and Graphene Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.