Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
by Staff Writers
Teddington, UK (SPX) Aug 21, 2014
Researchers at the National Physical Laboratory (NPL) have discovered that the conductivity at the edges of graphene devices is different to that of the central material.
Local scanning electrical techniques were used to examine the local nanoscale electronic properties of epitaxial graphene, in particular the differences between the edges and central parts of graphene Hall bar devices. The research was published in Scientific Reports, an open access publication from Nature Publishing Group.
The researchers found that the central part of the graphene channel demonstrated electron conduction (n-doped), whereas the edges demonstrated hole conduction (p-doped). They were also able to precisely tune the conduction along the edges of the graphene devices using side-gates, without affecting the conductive properties at the centre.
At a smaller scale, these effects become more acute; when working at the submicron level, the altered properties may affect up to 25% of the material.
Although both n- and p-type semiconductors conduct electricity, different types of conduction need to be acknowledged in the development of any devices. Graphene is increasingly used in the electronics industry and new devices will need to accommodate these differences.
The inversion effects were greatest just after the graphene had been cleaned, indicating that the carrier inversion was caused by defects at the channel edge introduced by the plasma etching process used to form the graphene devices.
By contrast, a few hours after cleaning, the inversion effects were reduced as airborne molecules had adsorbed onto the uncoupled bonds at the edges of the graphene.
The results of this study are useful for developing graphene nanoribbon devices as well as for looking at edge photocurrents and the quantum Hall effect.
The team is extending its work by investigating these effects in structurally different forms of graphene. In doing so, they will be able to compare different types of graphene and look more closely at the cause of these effects.
National Physical Laboratory
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|