University of Cincinnati
Department of Electrical Engineering and Computer Science
Cincinnati, Ohio, US
PhD Electrical Engineering, Purdue University, December 1987
MS Physics, Purdue University, December 1986
BS Physics, University of Liege, Belgium, July 1981
Marc teaches classes on Network Analysis, Electronics, Quantum Systems and Quantum Computing and performs research in nanoelectronics and vacuum microelectronics.
Advice to Students:
“Many new nanotechnology developments are increasingly encompassing areas as diverse as mathematics, physics, engineering, material science, chemistry, and even biology. I would suggest high-school students to choose their curriculum accordingly to encompass as many as possible of these areas.”
Q: In which Nanotechnology technical fields does your work apply best?
Modeling and Simulation
Q: When did you first find that your career path focused on nanotechnology?
Cahay: After joining Purdue University as a graduate student in 1983, I spent the summer of 1984 at the Amoco Research Center in Naperville-Illinois performing research on calculating the current through nanoscale devices (resonant tunneling devices and superlattices). In the Fall of 1984, I joined the group of Professor Datta at Purdue to keep working on this exciting field of research. The title of my Ph.D thesis is “Quantum Mechanical Analysis of Ultra-Small Devices”. I have done research in nanoelectronics ever since.
Q: What current nanotechnology applications are you working on?
Cahay: For the last ten years, I have been working in the field of spintronics, modeling various kinds of spin based field effect transistors. I have also done some experimental work in organic spintronics. My other area of research involves the measurements and theoretical modeling of field emission from carbon nanotube arrays and fibers.
Q: What’s the most rewarding thing about working with nanotechnology?
Cahay: Nanoscience and Nanotechnology are rapidly expanding fields. I keep reminding my students that this is the Nanomillenium. After nearly 36 years of research, I am still excited about nanotechnology because new concepts and areas of research are being discovered nearly on a weekly basis. Staying competitive is quite challenging and is best accomplished by forming teams to work in new areas where a blend of knowledge in materials science, physics, engineering, chemistry, and sometimes biology may be needed. Collaboration seems to be the surviving approach nowadays.
Q: Is there an example you can provide that shows how something you’ve worked on has positively impacted the world?
Cahay: My Ph.D thesis dealt with the self consistent modeling of resonant tunneling devices. Some of the results were published in a paper titled “Importance of Space-Charge Effects in Resonant Tunneling Devices”, Appl. Phys. Letters 50(10), pp.612-614 (1987). It has been cited over 175times as one of first self-consistent quantum-mechanical calculation of the current-voltage characteristics of nanoscale devices taking into account space-charge effects. This paper laid the foundation for a well-known modeling approach popularly known as SEQUAL (Semiconductor Electrostatics by QUantum-mechanical AnaLysis) used by universities and industries worldwide. It is now freeware available on the NSF-sponsored nanohub website at Purdue University and has been downloaded countless times by researchers worldwide.
Q: What do you think is the single greatest impact nanotechnology has had already had on the world?
Cahay: One of the earliest success in nanotechnology resulted from the discovery of the phenomenon of giant magnetoresistance (GMR) observed in thin-film structures composed of alternating ferromagnetic and non-magnetic conductive layers in the late 1980s by two independent groups led by Albert Fert in France and Peter Grünberg in Germany. They were awarded the 2007 Noble Prize in physics for this important discovery. GMR applications include the development of magnetic field sensors used to read data in hard disk drives, biosensors, and microelectromechanical systems (MEMS), among others. GMR multilayer structures are also used in magnetoresistive random-access memory (MRAM) as cells that store one bit of information. These are rapidly expanding billion dollar industries impacting our daily life.
Q: Over the past decade, nanotechnology has moved out of the lab and is making a real impact in society. Have you worked on any efforts that helped to commercialize nanotechnology and resulted in new products or processes? Please provide an example.
Cahay: Over the last few years, I have studied the field emission characteristics of carbon nanotube fibers which constitute a new type of cold cathodes with applications in electron microscopy, electron beam lithography, novel X-ray sources, vacuum electronic devices, terahertz sources, and high-power microwave tubes. Recently, I co-edited a book on “Nanotube Superfiber Materials – Manufacturing and Commercialization“ with M. Schulz, V. Shanov, J. Yin from the University of Cincinnati, published by Elsevier in 2018.
Q: In which areas do you anticipate future commercialization of nanotechnology having the greatest positive impact on the world?
Cahay: There is an increased interest for new types of sensors based on nanoparticles either attached to or embedded into other low dimensional or bulk samples. These sensors are able to detect minute amount of particles and should received a wide variety of electrical, mechanical, chemical and biological applications.
Q: Did your university training help you in your nanotechnology work?
Cahay: My Ph.D consisted in the modeling of electron transport in nanoscale devices. Since then, I have applied this training to the modeling of holes through the emitter-base junction of heterojunction bipolar transitors, the analysis of superconducting field effect transistors, field emission from various nanostructures, including carbon nanotubes and, more recently, to the investigation of spin transport in various nanostructures.
Q: Do you have a mentor? Did you in your college years?
Cahay: My mentor at Purdue was Professor Datta with whom I have conversed since then on various areas of nano research because I value his vast knowledge, and his insight and deep understanding of carrier transport at the nanoscale. Over the years, Professor Punit Boolchand at the Unversity of Cincinnati has helped be develop an experimental program in the field of vacuum nanoelectronics. I also benefit from the expertise of Walter Friz who introduced me to the rare earth monosulfides for cold cathode applications. Lately, I have benefited from the interaction with the late George Purdy and with Dennis Morris in the UK on the use of quaternions and their use in quantum mechanics.
Q: If you had to do it all over again, would you still focus on nanotechnology applications?
Cahay: I remember how fascinated I was learning for the first time about by quantum mechanics as an undergraduate student in Physics at the University of Liege, Belgium. In one month I had read most of the first volume of the quantum mechanics textbook by Cohen-Tannoudji, neglecting most of my other classes. I have kept the same excitement over the years about nanotechnology. Learning about a new area is often an uphill battle because of the vast amount of reading needed before coming up with new ideas but, once that hurdle is passed and funding can be secured in a specific area, the work is very exciting and rewarding.
Q: If a high school or college student was interested in nanotechnology, what advice would you give them to help prepare take on those roles?
Cahay: Many new nanotechnology developments are increasingly encompassing areas as diverse as mathematics, physics, engineering, material science, chemistry, and even biology. I would suggest high-school students to choose their curriculum accordingly to encompass as many as possible of these areas. I would strongly advise to participate into regional and national high-school science fairs to broaden their views about nanotechnology. Also many professors at universities seek the help of high-school students to perform research during the summer. It is a very valuable experience to work in a true research environment and to be exposed at an early age to the various aspects of state-of-the art nanoresearch facilities. The effort put in at an early age should help the students secure acceptance in some of the best schools around the country and launch them into a successful and hopefully pioneering career in nanotechnology.