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Gallium Arsenide P-I-N Detectors for High-Sensitivity Imaging of Thermal Neutrons--Spire Corporation, One Patriots Park, Bedford, MA 01730-2396; 781-275-6000
Mr. Stanley M. Vernon, Principal Investigator
Dr. Everett S. McGinley, Business Official
DOE Grant No. DE-FG02-98ER82672
Amount: $750,000
In addition to nuclear physics research, neutron radiography is important for such applications as personnel safety, energy exploration, industrial control, and detecting illicit materials. Current technologies are slow and cumbersome. A portable, room-temperature device yielding digital data output would significantly advance the state of the art. This project will develop gallium arsenide (GaAs) p-i-n detectors using high-quality layers epitaxially deposited by metalorganic chemical vapor deposition. P-I-N diodes have much lower dark-current than the Schottky barrier designs studied previously, resulting in much greater signal-to-noise ratios. Phase I developed individual GaAs p-i-n diodes with very low carrier concentrations and fabricated these into boron-coated neutron detectors. These were shown to have neutron detection efficiencies up to 2%, high gamma-ray rejection, and dark currents as low as 10 e-11 amps per square centimeter. Phase II will improve the performance of the GaAs p-i-n diode by optimizing the back-surface field and the device fabrication process. Multi-element arrays will be developed and tested in neutron radiography applications.
Commercial Applications and other Benefits as described by the awardee: Commercial applications for these neutron radiography systems include the imaging of low-density materials inside high-density containers. This ability yields many benefits in industrial control, radiation safety, and detection of illicit materials.