Crystal Growth and Characterization of Semiconductors and Scintillators

The Materials Science and Applcations Group has continues its excellent work as indicated in the following areas of accomplishment:

• The characterization method based on the Pockels electro-optic effect expanded to include controlled temperature and laser or LED illumination. This capability allows us to work with Savannah River National Lab in a project where we utilize LED illumination to control the internal electric field and charge trapping. Parallel measurement is done on an actual CZT gamma spectrometer to assess the feasibility of improving the energy resolution of the spectrometer.
• Preliminary investigations of new materials were performed and we have synthesized and grown LiGaSe2 and LiGaTe2. The work is supported by a grant from the Department of Energy supporting a collaboration between Fisk and Y-12 National Security Complex. These materials are semiconductors with a good potential of being demonstrated as first lithium containing compound semiconductors with important applications for neutron detectors.
• Exploratory work lead to the discovery of a new scintillator n collaboration with scientists at LLNL: Crystal of SrI2(Eu2+) have been grown at Fisk and have been demonstrated as a new material that has the highest light yield of all known scintillators (~100,000 photons/MeV) and was already demonstrated to match the energy resolution of the best commercial scintillators, 2.6% at 662 keV.