Photocurrents in the polar phase of K1-xLixTaO3

Experiments on photoconductivity and thermally stimulated currents were performed on Li-doped KTaO3 single crystals. The large enhancement of conductivity, caused by UV excitation at low temperature was found to correlate with a subsequent release of trapped charge between 30 and 40 K. No corresponding release was shown by pure KTaO3, consistently with a very low yield of photoconduction. It is concluded that the presence of hole traps, with the consequent quenching of electron-hole recombination, is at the origin of the photoconductive response of K1−xLixTaO3.