Speakers: Joerg Appenzeller and Zhihong Chen
The speakers from Purdue University will explore graphene and the emerging family of two-dimensional materials that may help shape the future of electronics. They will explain what makes graphene scientifically unusual, why its extraordinary electrical and physical properties generated such excitement, and which proposed applications appear genuinely promising. Drawing on their research in nanoelectronics, low-dimensional materials, advanced devices, and carbon-based technologies, they will also discuss the technical and manufacturing obstacles that have limited graphene’s widespread commercial adoption. The presentation will place graphene in the broader context of newer 2D materials and describe what Purdue researchers are learning about how these materials may complement—or in some applications eventually move beyond—conventional silicon technology.
Dr. J. Appenzeller received the M.S. and Ph.D. degrees in physics from the Technical University of Aachen, Germany in 1991 and 1995. In 2014 he became the Barry M. and Patricia L. Epstein Professor of Electrical and Computer Engineering. His current interests include novel devices based on low-dimensional nano-materials as nanowires, nanotubes, graphene and di-chalcogenides.
Dr. Chen received the B.S. degree in physics from Fudan University, China, in 1998, and the M.S. and Ph.D. degrees in physics from the University of Florida in 2002 and 2003, respectively.
In 2010, she joined Purdue University as an Associate Professor of Electrical and Computer Engineering and became a full Professor in 2017. Since 2023, she has served as the Mary Jo and Robert L. Kirk Director of the Birck Nanotechnology Center and is currently the Reilly Professor of Electrical and Computer Engineering. Her research interests include the exploration and manipulation of low-dimensional and other novel nanomaterials for nano electronic applications, two dimensional electronic devices, advanced interconnect technologies, spintronic devices, and the design and fabrication of novel nanoscale devices and circuits.
Sponsored by Doug Ellrich
Program: Graphene and 2D Materials: Promise, Problems, and the Future of Electronics
Speaker: Drs. Joerg Appenzeller and Zhihong Chen, Purdue Birck Nanotechnology Center
Introduced By: Doug Ellrich
Attendance: NESC: 117; Zoom: 31
Guests: Dick Yoho, Steve Cole, Melody Kissling, Rick Kissling, H. Tesser, Nathaniel Fried, Cordelia Elemeln, Lara Tervet, Rupert Ellmeln, Marco Miller
Scribe: Terry Ihnat
Editor: Ed Nitka
Talk’s Zoom recording found at: https://www.scientechclubvideos.org/zoom/08172026.mp4
The presentation explored graphene and other two-dimensional materials that could shape the future of electronics. The presenters explained graphene’s useful properties, applications and the technical and manufacturing challenges that have limited its commercial use. They also examined newer two-dimensional materials and how they may complement or eventually move beyond traditional silicon technology.
Graphene is an allotrope of carbon; it occurs naturally in small amounts. Carbon atoms form a sheet of interlocked atoms as a hexagon one atom thick. It resembles the face of a honeycomb. It is transparent. When hundreds of layers build up it forms graphite. Graphene has a high tensile strength, high electrical conductivity, and 97% of light passes through it. It is the thinnest two-dimensional material in the world and one of the strongest materials ever measured. It is bendable and can form carbon nanotubes which are tubes made of graphene with the high tensile strength and thermal conductivity secondary to the nanostructure and strength of the bonds between the carbon atoms. These nanotubes can be single walled and are formed by rolling graphite graphene sheets into a tube. Graphene is a two-dimensional semi-metal and carbon nanotubes can be either metals or semiconductors having to do with the tubular axis.
Some of the uses proposed for this technology are touch screens, flexible electronics, high frequency transistors, super supercapacitors, lithium-ion batteries, and solar cells. There are challenges to the reliable and economic manufacturing of high-quality single layer carbon. The market is not large enough yet, but if it increased it could justify investment. At the present time the global semiconductor market is in the trillions of dollars.
The speakers talked about the chemistry. Metals are generally shiny electrical conductors through which electrons flow like rivers. Semiconductors can be thought of as flood gates that slow electron movement and insulators that prevent electron flow. Semiconductors can be made of carbon, silicon or germanium as in silicon transistors. The speakers introduced the term band gap, insulators having a large band gap. Conductors have valence and conductivity bands that may overlap, and some substances may be an insulator at 0 degrees Kelvin but allow thermal excitation of electrons as the temperature raises towards the melting point. The tendency is for transistors to become smaller and more powerful allowing more functionality in a smaller space.
There was a question about manufacturing these sevices in space. There would be the benefits of a vacuum, cleanliness, and no gravity all of which could help manufacturing, but there is a lot to be worked out.
As semiconductor technology gets more efficient it could cut down on some of the power used in data centers.
Dr. Zhihong Chen
Dr. Joerg Appenzeller
