{"171751":{"#nid":"171751","#data":{"type":"news","title":"Fabrication on Patterned Silicon Carbide Produces Bandgap for Graphene-Based Electronics","body":[{"value":"\u003Cp\u003EBy fabricating graphene structures atop nanometer-scale \u201csteps\u201d etched into silicon carbide, researchers have for the first time created a substantial electronic bandgap in the material suitable for room-temperature electronics. Use of nanoscale topography to control the properties of graphene could facilitate fabrication of transistors and other devices, potentially opening the door for developing all-carbon integrated circuits.\u003C\/p\u003E\u003Cp\u003EResearchers have measured a bandgap of approximately 0.5 electron-volts in 1.4-nanometer bent sections of graphene nanoribbons. The development could provide new direction to the field of graphene electronics, which has struggled with the challenge of creating bandgap necessary for operation of electronic devices.\u003C\/p\u003E\u003Cp\u003E\u201cThis is a new way of thinking about how to make high-speed graphene electronics,\u201d said Edward Conrad, a professor in the School of Physics at the Georgia Institute of Technology. \u201cWe can now look seriously at making fast transistors from graphene. And because our process is scalable, if we can make one transistor, we can potentially make millions of them.\u201d\u003C\/p\u003E\u003Cp\u003EThe findings were reported November 18 in the journal \u003Cem\u003ENature Physics\u003C\/em\u003E. The research, done at the Georgia Institute of Technology in Atlanta and at SOLEIL, the French national synchrotron facility, has been supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Georgia Tech, the W.M. Keck Foundation and the Partner University Fund from the Embassy of France.\u003C\/p\u003E\u003Cp\u003EResearchers don\u2019t yet understand why graphene nanoribbons become semiconducting as they bend to enter tiny steps \u2013 about 20 nanometers deep \u2013 that are cut into the silicon carbide wafers. But the researchers believe that strain induced as the carbon lattice bends, along with the confinement of electrons, may be factors creating the bandgap. The nanoribbons are composed of two layers of graphene.\u003C\/p\u003E\u003Cp\u003EProduction of the semiconducting graphene structures begins with the use of e-beams to cut \u201ctrenches\u201d into silicon carbide wafers, which are normally polished to create a flat surface for the growth of epitaxial graphene. Using a high-temperature furnace, tens of thousands of graphene ribbons are then grown across the steps, using photolithography.\u003C\/p\u003E\u003Cp\u003EDuring the growth, the sharp edges of trenches become smoother as the material attempts to regain its flat surface. The growth time must therefore be carefully controlled to prevent the narrow silicon carbide features from melting too much.\u003C\/p\u003E\u003Cp\u003EThe graphene fabrication also must be controlled along a specific direction so that the carbon atom lattice grows into the steps along the material\u2019s \u201carmchair\u201d direction. \u201cIt\u2019s like trying to bend a length of chain-link fence,\u201d Conrad explained. \u201cIt only wants to bend one way.\u201d\u003C\/p\u003E\u003Cp\u003EThe new technique permits not only the creation of a bandgap in the material, but potentially also the fabrication of entire integrated circuits from graphene without the need for interfaces that introduce resistance. On either side of the semiconducting section of the graphene, the nanoribbons retain their metallic properties.\u003C\/p\u003E\u003Cp\u003E\u201cWe can make thousands of these trenches, and we can make them anywhere we want on the wafer,\u201d said Conrad. \u201cThis is more than just semiconducting graphene. The material at the bends is semiconducting, and it\u2019s attached to graphene continuously on both sides. It\u2019s basically a Shottky barrier junction.\u201d\u003C\/p\u003E\u003Cp\u003EBy growing the graphene down one edge of the trench and then up the other side, the researchers could in theory produce two connected Shottky barriers \u2013 a fundamental component of semiconductor devices. Conrad and his colleagues are now working to fabricate transistors based on their discovery.\u003C\/p\u003E\u003Cp\u003EConfirmation of the bandgap came from angle-resolved photoemission spectroscopy measurements made at the Synchrotron CNRS in France. There, the researchers fired powerful photon beams into arrays of the graphene nanoribbons and measured the electrons emitted.\u003C\/p\u003E\u003Cp\u003E\u201cYou can measure the energy of the electrons that come out, and you can measure the direction from which they come out,\u201d said Conrad. \u201cFrom that information, you can work backward to get information about the electronic structure of the nanoribbons.\u201d\u003C\/p\u003E\u003Cp\u003ETheorists had predicted that bending graphene would create a bandgap in the material. But the bandgap measured by the research team was larger than what had been predicted.\u003C\/p\u003E\u003Cp\u003EBeyond building transistors and other devices, in future work the researchers will attempt to learn more about what creates the bandgap \u2013 and how to control it. The property may be controlled by the angle of the bend in the graphene nanoribbon, which can be controlled by altering the depth of the step.\u003C\/p\u003E\u003Cp\u003E\u201cIf you try to lay a carpet over a small imperfection in the floor, the carpet will go over it and you may not even know the imperfection is there,\u201d Conrad explained. \u201cBut if you go over a step, you can tell. There are probably a range of heights in which we can affect the bend.\u201d\u003C\/p\u003E\u003Cp\u003EHe predicts that the discovery will create new activity as other graphene researchers attempt to utilize the results.\u003C\/p\u003E\u003Cp\u003E\u201cIf you can demonstrate a fast device, a lot of people will be interested in this,\u201d Conrad said. \u201cIf this works on a large scale, it could launch a niche market for high-speed, high-powered electronic devices.\u201d\u003C\/p\u003E\u003Cp\u003EIn addition to Conrad, the research team included J. Hicks, M.S. Nevius, F. Wang, K. Shepperd, J. Palmer, J. Kunc, W.A. De Heer and C. Berger, all from Georgia Tech; A. Tejeda from the Institut Jean Lamour, CNES \u2013 Univ. de Nancy and the Synchrotron SOLEIL; A. Taleb-Ibrahimi from the CNRS\/Synchrotron SOLEIL, and F. Bertran and P. Le Fevre from Synchrotron SOLEIL.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis research was supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Georgia Tech under Grants DMR-0820382 and DMR-1005880, the W.M. Keck Foundation, and the Partner University Fund from the Embassy of France. The content of the article is the responsibility of the authors and does not necessarily represent the views of the National Science Foundation.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Hicks, J., A wide-bandgap metal-semiconductor-metal nanostructure made entirely from graphene, Nature Physics (2012). \u003Ca href=\u0022http:\/\/dx.doi.org\/10.1038\/NPHYS2487\u0022 title=\u0022http:\/\/dx.doi.org\/10.1038\/NPHYS2487\u0022\u003Ehttp:\/\/dx.doi.org\/10.1038\/NPHYS2487\u003C\/a\u003E.\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30332-0181\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E)\u003Cbr \/\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EBy fabricating graphene structures atop nanometer-scale \u201csteps\u201d etched into silicon carbide, researchers have for the first time created a substantial electronic bandgap in the material suitable for room-temperature electronics. Use of nanoscale topography to control the properties of graphene could facilitate fabrication of transistors and other devices, potentially opening the door for developing all-carbon integrated circuits.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers have created a substantial electronic bandgap in graphene suitable for room-temperature electronics."}],"uid":"27303","created_gmt":"2012-11-16 18:31:03","changed_gmt":"2016-10-08 03:13:14","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2012-11-18T00:00:00-05:00","iso_date":"2012-11-18T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"171721":{"id":"171721","type":"image","title":"Graphene bandgap","body":null,"created":"1449178999","gmt_created":"2015-12-03 21:43:19","changed":"1475894811","gmt_changed":"2016-10-08 02:46:51","alt":"Graphene bandgap","file":{"fid":"195736","name":"graphene-bandgap.jpg","image_path":"\/sites\/default\/files\/images\/graphene-bandgap_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/graphene-bandgap_0.jpg","mime":"image\/jpeg","size":178253,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/graphene-bandgap_0.jpg?itok=TJK89hIQ"}},"171731":{"id":"171731","type":"image","title":"Graphene bandgap2","body":null,"created":"1449178999","gmt_created":"2015-12-03 21:43:19","changed":"1475894811","gmt_changed":"2016-10-08 02:46:51","alt":"Graphene bandgap2","file":{"fid":"195737","name":"graphene-bandgap2.jpg","image_path":"\/sites\/default\/files\/images\/graphene-bandgap2_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/graphene-bandgap2_0.jpg","mime":"image\/jpeg","size":205398,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/graphene-bandgap2_0.jpg?itok=YEVzPeU4"}},"171741":{"id":"171741","type":"image","title":"Graphene bandgap3","body":null,"created":"1449178999","gmt_created":"2015-12-03 21:43:19","changed":"1475894811","gmt_changed":"2016-10-08 02:46:51","alt":"Graphene bandgap3","file":{"fid":"195738","name":"graphene-bandgap3.jpg","image_path":"\/sites\/default\/files\/images\/graphene-bandgap3_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/graphene-bandgap3_0.jpg","mime":"image\/jpeg","size":144655,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/graphene-bandgap3_0.jpg?itok=Mjz0Rgm0"}}},"media_ids":["171721","171731","171741"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"150","name":"Physics and Physical Sciences"}],"keywords":[{"id":"50751","name":"bandgap"},{"id":"50761","name":"Ed Conrad"},{"id":"9116","name":"epitaxial graphene"},{"id":"429","name":"graphene"},{"id":"432","name":"nanoribbon"},{"id":"166937","name":"School of Physics"},{"id":"169534","name":"silicon carbide"}],"core_research_areas":[{"id":"39451","name":"Electronics and Nanotechnology"},{"id":"39471","name":"Materials"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News \u0026amp; Publications Office\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}