Low temperature luminescence of ZnMoO4 single crystals grown by low temperature gradient Czochralski technique

ZnMoO4 single crystals of high optical quality were grown using low temperature gradient Czochralski technique and their luminescence properties were studied. At low temperatures two overlapping luminescence bands with the maxima 1.93 eV and 2.45 eV were detected at Eex > 3.9 eV. The bands are attributed to the radiative recombination of self-trapped excitons of MoO42- parentage. High-intensity non-elementary peak of thermostimulated luminescence (TSL) observed at 65 K is due to the thermal release of self-trapped holes. The threshold of TSL excitation spectrum at 6.2 eV exceeds the bandgap value by 1.9 eV and corresponds to electronic transitions from the valence band to the upper subband of the conduction band.

► Colorless single crystals of ZnMoO4 were grown for the first time.
► Two emission bands were observed and ascribed to the self-trapped excitons.
► TSL peak at 65 K is ascribed to the thermal release of self-trapped holes.
► Origin of the threshold in TSL excitation spectrum is explained.