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January 7, 2016鈥擜 team of researchers from Georgetown University and the (NRL) have found a new way to detect millimeter-wavelength radiation with 100,000 times more sensitive than conventional technology. Georgetown 海角论坛 Associate Professor of and her team published their findings in the , a multidisciplinary journal dedicated to nanoscience and nanotechnology.

Terahertz radiation has wavelengths ranging from tens of micrometers to a few millimeters and is not visible to the human eye. Although it is difficult to detect, terahertz radiation can penetrate skin, muscles, and teeth to provide information on abnormalities in humans and animals. 鈥淭here are not many detectors or powerful sources for terahertz. This type of radiation can be used for applications in many fields, from medical or security imaging (it can penetrate most nonconducting materials like clothing or plastic, without the damaging ionization effects of x-rays) to spectroscopy (it can be used to identify the chemical composition of compounds),鈥� Barbara said.

To see this radiation, scientists use a tool called a bolometer. Barbara and Dr. Abdel El Fatimy, a postdoctoral fellow at Georgetown, worked in collaboration with Dr. Kurt Gaskill鈥檚 group at NRL to create a bolometer using small area devices known as quantum dots. The dots are made from graphene, a two-dimensional form of carbon that is one atomic layer thick and has 鈥渆xtraordinary electronic and optical properties,鈥� Barbara explained. The dots have dimensions 500 times smaller than the width of a human hair (or less than a tenth of a micrometer) and have extraordinarily high sensitivity to two-millimeter wavelength radiation.

Starting with high-quality graphene grown at NRL, the quantum dots were produced using standard semiconductor device processing techniques at the (GN渭Lab), a state-of-the-art facility in Regents Hall. 鈥淭his [production method] means it is possible to integrate antennas to the quantum-dot detector using straightforward methods,鈥� said Gaskill, who leads a research group at NRL. 鈥淭he addition of an antenna will further improve the sensitivity of the quantum-dot detectors,鈥� he continued. Because the graphene is uniform, many individual detectors or arrays of detectors with similar properties can be fabricated at one time.

鈥淭he ability to make materials that are just one atom thick and to build electronic devices with them presents new opportunities,鈥� Barbara continued. 鈥淕raphene quantum dots were studied before, but never as bolometers. Their extraordinary performance and ease of fabrication are a technological breakthrough.鈥�

Related Information

The article, 鈥淓pitaxial graphene quantum dots for high-performance terahertz bolometers,鈥� was published in the . The authors are Abdel El Fatimy, Rachael L. Myers-Ward, Anthony K. Boyd, Kevin M. Daniels, D. Kurt Gaskill, and Paola Barbara. The study was developed with funding from the Office of Naval Research and the Air Force Office of Scientific Research.

Image: The artist鈥檚 impression shows a graphene layer patterned with a circular quantum dot in the center. The graphene is exposed to terahertz radiation and connected to electrical contacts to measure the electrical output signal. (Image courtesy of Abdel El Fatimy and Oliver Albertini.)