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Photoconductivity spectra of PbWO4 Crystals

Abstract By controlling the crystal growth atmosphere, two kinds of PbWO4 single crystals with different colors have been obtained. We present the results of optical spectroscopy and photoconductivity measurements of such PbWO4 crystals in the UV-VIS range. The optical absorption and photoconductivity spectra of the yellow colored crystals show additional spectral responses around 420 and 350 nm as compared with those of the colorless crystals. We attribute such additional features of the colored crystals to a stoichiometric deficiency of Pb ions, resulting in the formation of two impurity states of Pb3+ and O− Those impurity states act as color centers for the optical transitions, and also as trap sources for the exciton dissociation, contributing to the photocurrent response even in the energy range of the exciton formation.