CORRELATIONS BETWEEN MERCURIC IODIDE PHOTOLUMINESCENCE SPECTRA AND NUCLEAR-DETECTOR PERFORMANCE

Low temperature photoluminescence spectroscopy was performed on a variety of HgI2 samples and also on graded HgI2 nuclear detectors. Correlations were found between features in the photoluminescence spectra and a crystal's ability to produce high-quality detectors. The intensity of a broad emission band centered at 6200 angstrom (designated as band 3) is weaker in crystals that yield high-quality detectors. Therefore, the defects responsible for this emission band are undesirable in the fabrication of HgI2 nuclear detectors. The measurements also revealed that stronger emission in the exciton region (designated as band 1) is associated with crystals which Produce high-quality detectors, indicating that a high degree of structural perfection is important for HgI2 detector applications. These correlations, together with. earlier results from studies of processing-induced defects, lead to suggestions regarding improvement of the manufacturing yield of high-quality HgI2 detectors.