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Novel Devices Thickness of graphene on SiC no longer an enigma


New developments have shown that the thickness of graphene on SiC can be measured using Electrostatic Force Microscopy in ambient conditions.


Scientists from NPL, in collaboration with Linköping University, Sweden, have shown that regions of graphene of different thickness can be easily identified in ambient conditions using Electrostatic Force Microscopy (EFM).


The exciting properties of graphene are usually only applicable to the material that consists of one or two layers of the graphene sheets. Whilst synthesis of any number of layers is possible, the thicker layers have properties closer to the more common bulk graphite.


Further details of this work can be seen in the article “Mapping of Local Electrical Properties in Epitaxial Graphene Using Electrostatic Force Microscopy” by Burnett et al, Nano Letters.


DOI: 10.1021/nl200581g


Berlin to host compound semiconductor conference


Organised by the Fraunhofer Institute and the VDE Association for Electrical Technologies, Electronic & Information Technologies, the conference will address the future of compound semiconductors in micro electronics and optoelectronics.


On May 23, 2011, Andre Geim, the 2010 winner of the Nobel Prize in Physics, opened the 2011 Compound Semiconductor Week with a plenary lecture on graphene.


Here, some 450 scientists and industry representatives will discuss current research findings in the field of compound semiconductors. An example of one of the key topics of the event is how to improve energy efficiency while increasing data rates in communications systems – often referred to as “Green IT”.


For device applications one- and two-layer graphene needs to be precisely identified apart from the substrate and regions of thicker graphene. Exfoliated graphene sheets up to ~100 μm in size can be routinely identified by optical microscopy.


However, the situation is much more complicated in the case of the epitaxial graphene grown on SiC wafers with a diameter up to 5 inches where the straightforward identification of the graphene thickness is difficult using standard techniques.


This research shows that EFM, which is one of the most widely accessible and simplest implementations of scanning probe microscopy, can clearly identify different graphene thicknesses. The technique can also be used in ambient environments applicable to industrial requirements.


The conference took place in Berlin from May 22 to 26. The conference was organised by the Fraunhofer Heinrich Hertz Institute HHI, the Fraunhofer Institute for Applied Solid State Physics IAF, and the VDE Association for Electrical Technologies, Electronic & Information Technologies.


“CSW is the most important international conference for the entire spectrum of compound semiconductors. Here, participants will get an overview of what will become possible in micro electronics and optoelectronics,” Oliver Ambacher, ISCS 2011 Conference Chair and head of the Fraunhofer IAF, said.


While silicon is still the most important semiconductor material, today no mobile phone, PC or car would work without additional components used in compound semiconductor technology. Compound semiconductor, in contrast to the elemental semiconductor – like silicon -, consists of


October 2011 www.compoundsemiconductor.net 199


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