Graphene theory devices and applications Ben Bowman EE 4611 4/10/17

What is Graphene? Graphene is a single layer of carbon atoms, a 2 dimensional material, first produced by Andre Geim and Kostya Novoselov. It has some unique properties such as being super strong and super conductive. These properties on top of being a 2 dimensional material makes it possibly useful for many things, and could revolutionizing fields. http://www.electrochem.org/dl/interface/spr/spr11/spr11_p047-052.pdf

Producing Graphene Exfoliation – removing layers at a time until you are left with graphene, can be slow, liquid exfoliation is faster but results in more defects. Chemical Vapor Deposition – Under various conditions, such as heat or pressure, gasses are grown on a substrate such as silicon. Currently most used technique, can be tricky to make uniform level graphene, and to remove the graphene from the substrate. New techniques are constantly being discovered such as one by researchers at Kansas State University which works by putting a some material that contains carbon with acetylene and oxygen, and ingite it producing graphene residue.

Graphene Transistors Graphene could have the potential to create very high performance transistors, however they do have problems, largely graphene does not have a band gap. http://www.nature.com/nnano/journal/v5/n7/full/nnano.2010.89.html http://www.electrochem.org/dl/interface/spr/spr11/spr11_p047-052.pdf

Adjusting the bandgap A bandgap can be created in a few ways Using small nanoribbon graphene pieces. Straining the Graphene. Layering two sheets of Graphene on top of each other, with an electric field running perpendicular two the sheets. Another promising solution involves layering two sheets of Graphene with a dielectric layer, that under certain biasing's will act as a short and other biasing's will act as a open connection between the layers. http://www.nature.com/nnano/journal/v5/n7/full/nnano.2010.89.html

Applications of Graphene Solar cells – Graphene could have the potential to revolutionize solar panels, graphene's flexibility, ability to let light pass through, and graphene's conductivity all make it a good material for solar cells . Water filtration - Graphene can work as a filter, only allowing water through via osmosis. This can be used to create safe drinking water, or possibly be used for medical purposes. http://www.nextbigfuture.com/2012/06/water-desalination-across-nanoporous.html https://www.australiansolarquotes.com.au/2011/09/06/graphene-solar-cells/

Applications continued Graphene’s strength can be used for strong light building material, useful in many industries. Flexible Touchscreens – Graphene's flexibility can be used to have flexible touchscreens and can be scene in some cellphones. Energy Storage – Graphene's density allows for stacking to create very dense energy storage that could be used for better batteries. http://sciencenordic.com/dream-screen-just-around-corner

References Wonbong Choi , Indranil Lahiri , Raghunandan Seelaboyina & Yong Soo Kang (2010) Synthesis of Graphene and Its Applications: A Review, Critical Reviews in Solid State and Materials Sciences, 35:1, 52-71, DOI: 10.1080/10408430903505036 The Home of Graphene, The University of Manchester, www. graphene.manchester.ac.uk, accessed April 7 2017. Frank Schwierz, “Graphene transistors”, Nature Nanotechnology| review, 2010, http://www.nature.com/nnano/journal/v5/n7/full/nnano.2010.89.html. Apell, S. P., G. W. Hanson, and C. Hägglund. "Absorption Spectrum of Graphene." Graphene and Carbon Nanotubes (2013): 215-22. 2 Jan. 2012. Web. 7 Apr. 2017. <https://arxiv.org/ftp/arxiv/papers/1201/1201.3071.pdf>. Geim, A. K., & Novoselov, K. S. (2007). The rise of graphene. Nature Materials, 6(3), 183. Galeon, Dom. "We May Finally Have a Way of Mass Producing Graphene." Futurism. Ed. Partrick Caughill. Futrism, 28 Jan. 2017. Web. 07 Apr. 2017. <https://futurism.com/we-may-finally-have-a-way-of-mass-producing- graphene/>.

Reference continued Fuente, Jesus. "CVD Graphene - Creating Graphene Via Chemical Vapour Deposition."Graphenea. Graphenea, n.d. Web. 07 Apr. 2017. <https://www.graphenea.com/pages/cvd-graphene>. "Graphene Applications: What Is Graphene Used For?" Graphene Applications: What Is Graphene Used For? | Graphene-Info. Graphene-info, n.d. Web. 07 Apr. 2017. <http://www.graphene- info.com/graphene-applications>. "Graphene Solar: Introduction and Market News." Graphene Solar Panels: Introduction and Market Status | Graphene-Info. Graphene-info, n.d. Web. 07 Apr. 2017. <http://www.graphene- info.com/graphene-solar-panels>. Obeng, Y., and P. Srinivasan. "Graphene: Is It the Future for Semiconductors? An Overview of the Material, Devices, and Applications." Interface Magazine 20.1 (2011): 47-52. Web. 7 Apr. 2017.

5 Key points Graphene is a single layer of Carbon atoms. Graphene transistors have to adjust to Graphene naturally not having a band gap. Efficient production of Graphene is an issue and new ways of producing it are constantly being discovered. Graphene's strength and light weight makes it great as a material for many products. Graphene’s flexibility can be used to make flexible touchscreens which are used in some phones.