PHOTOCONDUCTIVITY IN KTAO3LI SINGLE-CRYSTALS

Photoconductive currents of the same order of magnitude as in conventi onal impurity-dope semiconductors have been observed at temperatures l ower than 80 K in the K1-xLixTaO3 (KTL) mixed system (with 0.016 less- than-or-equal-to x less-than-or-equal-to 0.05) and under light illumin ation with energy lower than the band gap. The dependence of the photo conductivity on temperature, Li concentration, and external electric f ield as well as on sample history and treatment is studied. The result s are interpreted and discussed on the basis of a model allowing a cal culation of the impurity levels taking into account the displacement o f the oxygen ions nearest to the off-center position of the Li+.