UMD Researchers Make Breakthrough in Terahertz Technology

A University of Maryland (UMD) research team, in collaboration with Monash University and the United States Naval Research Laboratory, has invented a Tunable Large Area Hybrid Metal-Graphene Terahertz Detector, an innovation based upon a successful demonstration of plasmonic resonance in graphene micro-ribbons that are connected to metal electrodes, offering a critical step toward practical graphene terahertz optoelectronic devices.

Graphene, a two-dimensional lattice of pure carbon, is extremely conductive and has unique and advantageous electronic and optical properties that are ideal for a variety of applications, such as sensors, oscillators, electronic components, filters, detectors, and more. Graphene is especially useful in terahertz range, the part of electromagnetic spectrum between microwaves and infrared light, because the free electrons in the material oscillate collectively at these frequencies. The resonance frequency can be tuned by applying an electric voltage at the gate. Being able to tune the resonance frequency allows the resonator to be adjusted, making it usable in a broad range of applications.

“Terahertz technology has a wide variety of potential scientific and commercial applications, ranging from medical diagnosis and screening, manufacturing, security screening, communications, and biochemical sensing,” said Thomas Murphy, Professor of Electrical and Computer Engineering (ECE) and Director of the Institute for Research in Electronics and Applied Physics (IREAP). The invention may offer a dramatic improvement in the ability to increase the speed of short range wireless communication, cutting the amount of time needed to stream a very high quality content between devices. It may offer means of improved security scanning at airports.

Until now, using graphene in terahertz sensors has primarily been theoretical because graphene must touch a metal surface to read out the results or tune the sensor, and this was previously thought to inhibit the plasmonic resonance. But the team invented a new design that does not inhibit charge accumulation at the contact and allows the signal to transfer from the graphene to the metal electrical contacts much more effectively.

The research team includes Murphy; ECE graduate student Mehdi Jadidi; United States Naval Research Laboratory researcher D. Kurt Gaskill; Michael Fuhrer, Research Professor in the Department of Physics and the Center for Nanophysics and Advanced Materials and Professor of Physics at Monash University in Australia; Andrei Sushkov, Assistant Research Scientist in the Department of Physics and the Center for Nanophysics and Advanced Materials; and H. Dennis Drew, Research Professor in the Department of Physics and the Center for Nanophysics and Advanced Materials.

Electrical connection or antenna coupling to graphene is a problem that has puzzled the researchers for many years, but the idea behind the team’s discovery originated with Jadidi.

The discovery has the potential to advance the field, and the team is excited to continue their research and further develop the technology in preparation for commercialization.

“We would be thrilled if this invention found near-term commercial applications,” said Murphy. “Perhaps the most promising short-term application would be for room-temperature tunable terahertz detectors.

The research was funded by the Office of Naval Research and National Science Foundation and was recently featured in the American Chemical Society’s journal, Nano Letters.

The invention has been nominated by UMD’s Office of Technology Commercialization for the Invention of the Year award in the Physical Sciences category at the Celebration of Innovation and Partnerships on May 9th as part of the University of Maryland’s “30 Days of EnTERPreneurship.”

To learn more about the University of Maryland’s “30 Days of EnTERPreneurship,” visit: http://www.umd.edu/30Days/.

Published May 6, 2016