Gallium Arsenide P-I_N Detectors for High-sensitivity Imaging of Thermal Neutrons

50332-98-I Gallium Arsenide P-I-N Detectors for High-Sensitivity Imaging of Thermal Neutrons--Spire Corporation, One Patriots Park, Bedford, MA 01730-2343; (781) 275-6000 Mr. Stanley M. Vernon, Principal Investigator Dr. Everett S. McGinley, Business Official DOE Grant No. DE-FG02-98ER82672 Amount: $74,932 Nuclear Physics research has a need for small, reliable, room-temperature thermal neutron detector arrays having improved performance in terms of higher sensitivity and lower dark currents. Such detectors are also needed for interrogation of radiation environments in such arenas as energy production, industry, research, treaty verification, and tracking of illicit materials. This project will develop a GaAs-based diode detector with a PIN junction (grown by metalorganic chemical vapor deposition), leading to improved performance over past designs which used Schottky barriers deposited directly on bulk GaAs semi-insulating wafers. Those wafers had poor carrier-transport properties (and lower sensitivity) compared with the high-quality epitaxially grown GaAs. Phase I will develop epitaxially grown GaAs diode structures, comparing both PIN-junction and Schottky barrier designs. Buffer layers of AlGaAs, to block unwanted carriers and getter impurities, will also be examined. Detectors, having boron-10 converter layers on the front, will be designed, fabricated, and tested in a flux of thermal neutrons. Commercial Applications and Other Benefits as described by the awardee: The detectors to be developed here will lead to reliable, room-temperature, high-sensitivity, low-bias, low-noise radiation-monitoring instrumentation for imaging neutron sources with high spatial resolution. Ultimately, integrated pixel arrays will be developed._