Woodruff School of Mechanical Engineering

NRE 8011/8012 and MP 6011/6012 Seminar

Nuclear & Radiological Engineering and Medical Physics Programs


Compound Semiconductor Radiation Detectors: Science Fiction, Horror Story, or Headlines?


Dr. Ralph James


Associate Laboratory Director for Science and Technology Chief Research Office, SRNL Fellow Savannah River National Laboratory, Aiken, SC


Thursday, February 4, 2021 at 11:00:00 AM   Add to Calendar


https://gatech.bluejeans.com/172812180 Building


Anna Erickson


Compound semiconductors are under investigation by many organizations for applications in the detection and imaging of X- and gamma-ray radiation. Such room-temperature-operating detectors are needed for a wide variety of medical and security uses. Among the different compound-semiconductor detectors available today, Cadmium Zinc Telluride (CdZnTe or CZT) is the most extensively studied due to its bandgap, high atomic number, and excellent charge-carrier transport properties. A two-pronged approach to advance the technology has been underway, (1) Identify and fix defects in the crystals by improving the growth and device fabrication processes, and (2) Use the best material for fabricating detectors and incorporating them into instruments for spectroscopy and imaging. A set of dedicated and unique tools were constructed for this R&D, most of which are applicable to other detector materials. This presentation will report data to understand defects created during growth and fabrication, distinguish various crystal imperfections and their effects on device performance, and deploy the detectors in field instruments for detection of special nuclear materials and localization of cancerous tumors. If time permits, I will briefly describe some of our recent results on alternative semiconductor detectors under study.


Dr. Ralph James is internationally recognized for his basic and applied research devoted to semiconductor materials, nonlinear optics, radiation detectors, spectroscopy, and imaging. He has authored more than 670 scientific publications, served as editor of 32 books, and holds 27 patents. The output of Dr. James’ research is finding numerous applications in the fields of materials science, gamma-ray spectrometers, nuclear medicine, solar energy, astrophysics, and security. In recognition of his achievements, he is a Fellow of the American Physical Society, Institute of Electrical and Electronic Engineers, American Association for the Advancement of Science, SPIE – The International Society of Optics and Photonics, Optical Society of America, and Materials Research Society. He currently serves as the Associate Laboratory Director for Science and Technology and the Chief Research Officer with Savannah River National Laboratory and is an SRNL Fellow. Previously, he served as the Associate Laboratory Director for the Energy, Environment and National Security Directorate with Brookhaven National Laboratory. Dr. James has received numerous international honors for his work on materials science, sensors and imaging, including Discover Magazine Innovator of the Year, 7 R&D100 awards, IEEE Outstanding Radiation Instrumentation Award, IEEE Harold Wheeler Award, Room-Temperature Semiconductor Scientist Award, Battelle Innovation Award, Frost & Sullivan Invention of the Year in prostate cancer, Long Technology Hall of Fame Inductee, ARCS Foundation Hall of Fame Inductee, Long Island Person of Year in Science, 2 Secretary of Energy Awards, among many others. He was also the President of SPIE, which is world’s largest society devoted to the science and applications of optics and photonics. Additionally, Dr. James served as Board Chairman of the Council of Scientific Society Presidents representing over 70 scientific societies and 1.4 million scientists and engineers across the globe. Dr. James received the B.S. degree in Engineering Physics from the Univ. of Tennessee, M.S. degree in Physics from Georgia Tech, and M.S. and Ph.D. degrees in Applied Physics from Caltech.