Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern July 21st, 2018

World's fastest man-made spinning object could help study quantum mechanics July 20th, 2018

Relax, just break it July 20th, 2018

Future electronic components to be printed like newspapers July 20th, 2018

Chemistry

Sirrus's Issued Patent Portfolio Continues To Accelerate July 18th, 2018

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides July 13th, 2018

The Institute of Applied Physics at the University of Tsukuba near Tokyo in Japan uses Deben's ARM2 detector to better understand catalytic reaction mechanisms June 27th, 2018

Quantum Interference May Be Key to Smaller Insulators: Breakthrough could jumpstart further miniaturization of transistors June 6th, 2018

Possible Futures

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern July 21st, 2018

World's fastest man-made spinning object could help study quantum mechanics July 20th, 2018

Relax, just break it July 20th, 2018

Future electronic components to be printed like newspapers July 20th, 2018

Nanoelectronics

GLOBALFOUNDRIES Surpasses $2 Billion in Design Win Revenue on 22FDX® Technology : With 50 client designs and growing, 22FDX proves its value as a cost-effective solution for power-sensitive applications July 9th, 2018

High-power electronics keep their cool with new heat-conducting crystals July 6th, 2018

Leti Presenting Strategic Vision and Hosting a Workshop at SEMICON West: “From Electrons to Photons” Leti Workshop and CEO Media Briefing Set for Tuesday, July 10 in W Hotel, San Francisco June 12th, 2018

Quantum Interference May Be Key to Smaller Insulators: Breakthrough could jumpstart further miniaturization of transistors June 6th, 2018

Discoveries

World's fastest man-made spinning object could help study quantum mechanics July 20th, 2018

Relax, just break it July 20th, 2018

Future electronic components to be printed like newspapers July 20th, 2018

The relationship between charge density waves and superconductivity? It's complicated July 19th, 2018

Announcements

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern July 21st, 2018

World's fastest man-made spinning object could help study quantum mechanics July 20th, 2018

Relax, just break it July 20th, 2018

Future electronic components to be printed like newspapers July 20th, 2018

Tools

Relax, just break it July 20th, 2018

The relationship between charge density waves and superconductivity? It's complicated July 19th, 2018

Oxford Instruments’ 22 Tesla superconducting magnet system commissioned at the UAM, making it the most intense magnetic field available outside a large international facility July 12th, 2018

Nanometrics to Announce Second Quarter Financial Results on July 31, 2018 July 12th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project