Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Graphene and gallium arsenide: two perfect partners find each other

The normally practically invisible single-carbon-atom layers can be made visible under a normal light (optical) microscope, if the support (layer) is designed as an anti-reflection filter. Single-layer graphene was identified inside the markings.
The normally practically invisible single-carbon-atom layers can be made visible under a normal light (optical) microscope, if the support (layer) is designed as an anti-reflection filter. Single-layer graphene was identified inside the markings.

Abstract:
PTB has for the first time made graphene visible on gallium arsenide - A successful combination of two unique electronic materials

Graphene and gallium arsenide: two perfect partners find each other

Berlin | Posted on September 21st, 2009

It is the marriage of two top candidates for the electronics of the future, both excentric and extremely interesting: Graphene, one of the partners, is an extremely thin fellow and besides, very young. Not until 2004 was it possible to specifically produce and investigate the single layer of carbon atoms. Its electronic properties are remarkable, because, among other things, its electrons can move so tremendously fast. It is a perfect partner for gallium arsenide, the semiconductor that allows tailoring of its electrical properties and which is the starting material of the fastest electrical and opto-electronic components. Besides, it is possible to produce gallium arsenide with an atomic-layer-smooth surface; this should suit well as a support for graphene. Scientists of the Physikalisch-Technische Bundesanstalt (PTB) have now, with the aid of a special design, succeeded in making graphene visible on gallium arsenide. Previously it has only been possible on silicon oxide. Now that they are able to view with a light optical microscope the graphene layer, which is thinner than one thousandth of a light wavelength, the researchers want to measure the electrical properties of their new material combination. As experts for precision measurements, the PTB physicists are thus especially well equipped to do this.

They use the principle of the anti-reflective layer: If on a material one superimposes a very thin, nearly transparent layer of another material, then the reflectivity of the lower layer changes clearly visibly. In order to make their lower layer of gallium arsenide (plus graphene atomic layer) visible, the PTB physicists chose aluminium arsenide (AlAs). However, it is so similar to gallium arsenide (GaAs) in its optical properties that they had to employ a few tricks: They vapour-coated not only one, but rather several wafer-thin layers. "Thus, even with optically similar materials it is possible, in a manner of speaking, to 'grow' interference effects", Dr. Franz-Josef Ahlers, the responsible department head at PTB, explained. "This principle is known from optical interference filters. We have adapted it for our purposes".

First of all, he and his colleagues calculated the optical properties of different GaAs and AlAs layers and optimized the layer sequence such that they could expect a sufficiently good detectability of graphene. Following this recipe, they got down to action and with the molecular beam epitaxial facility of PTB accurately produced a corresponding GaAs/AlAs crystal atom layer. Then in the same procedure as with silicon oxide, it was overlaid with graphite fragments. "Different from silicon but as predicted by the calculation, although single carbon layers are no longer visible at all wavelengths of visible light, it is, however, possible, e.g. with a simple green filter, to limit the wavelength range such that the graphene is easily visible", explained Ahlers. In the photo, all lighter areas of the dark GaAs are covered with graphene. From the degree of lightening it is possible to conclude the number of individual layers of atoms. The marked areas are 'real', that is, single-layer graphene. But next to them, there are also two, three and multiple layers of carbon atoms, which also have interesting properties. This arrangement was confirmed again with another method, Raman spectroscopy.

Following such a simple identification with a normal light optical microscope, the further steps in the manufacture of electrical components from graphene surfaces are now possible without any difficulty. Thus the PTB scientists can now begin to accurately measure the electrical properties of the new material combination.

The original publication:
Graphene on Gallium Arsenide: Engineering the visibility.
M. Friedemann, K. Pierz, R. Stosch, F. J. Ahlers.
Applied Physics Letters, Appl. Phys. Lett. 95,
DOI: 10.1063/1.3224910,
link.aip.org/link/?APL/95/102103

####

About Physikalisch-Technische Bundesanstalt
The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute providing scientific and technical services. PTB measures with the highest accuracy and reliability – metrology as the core competence.

For more information, please click here

Contacts:
Dr. Franz Josef Ahlers, PTB Department 2.6 Quantum Electrical Metrology,
phone: +49 531 592 2600,

Copyright © Physikalisch-Technische Bundesanstalt

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Bruker-Sponsored Sixth AFM BioMed Conference Highlights Increasing Impact of AFM in Biological Applications February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Chemistry

Chromium-Centered Cycloparaphenylene Rings as New Tools for Making Functionalized Nanocarbons February 24th, 2015

Stretch and relax! -- Losing 1 electron switches magnetism on in dichromium February 23rd, 2015

A straightforward, rapid and continuous method to protect MOF nanocrystals against water February 9th, 2015

Research shows benefits of silicon carbide for sensors in harsh environments: Advantages identified across industries February 9th, 2015

Possible Futures

European roadmap for graphene science and technology published February 25th, 2015

Quantum research past, present and future for discussion at AAAS February 16th, 2015

World’s first compact rotary 3D printer-cum-scanner unveiled at AAAS by NTU Singapore start-up: With production funded by crowdsourcing, the first unit will be delivered to the United States in March February 16th, 2015

Nanotechnology Electric Vehicle (EV) Market Analysis Report 2015: According to Radiant Insights, Inc February 13th, 2015

Nanoelectronics

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

Ultra-thin nanowires can trap electron 'twisters' that disrupt superconductors February 24th, 2015

Improved fire detection with new ultra-sensitive, ultraviolet light sensor February 17th, 2015

Nanotechnology facility planned in Lund, Sweden: A production facility for start-ups in the field of nanotechnology may be built in the Science Village in Lund, a world-class research and innovation village that is also home to ESS, the European Spallation Source February 15th, 2015

Discoveries

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Simple, Cost-Efficient Method Used to Determine Toxicants Growing in Pistachio February 26th, 2015

Warming up the world of superconductors: Clusters of aluminum metal atoms become superconductive at surprisingly high temperatures February 25th, 2015

Announcements

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

Bruker-Sponsored Sixth AFM BioMed Conference Highlights Increasing Impact of AFM in Biological Applications February 26th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Tools

Hiden CATLAB Microreactor System at ARABLAB 2015 | Visit us on Booth 1011 February 26th, 2015

Renishaw and Bruker team up for a workshop on TERS and co-localised AFM Raman February 26th, 2015

Maximum Precision in 3D Printing: New complete solution makes additive manufacturing standard for microfabrication February 26th, 2015

Real-time observation of bond formation by using femtosecond X-ray liquidography February 26th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE