Photoinduced charge transport in KTaO3:Be

We present the first growth of KTaO3:Be (6% at. in the batch) single crystals, together with photoconductivity and thermally stimulated currents studies of this material. It is probably that very small Be2+ ions (ionic radius 0.35 Å ) mostly substitute K+(1.64 Å) and bounded and/or free electronic states formation including polaronic states. As a results Be-doping effect can strongly influence phase instability and electronic properties of KTaO3. It was found that Be2+ doping leads to appreciable photocurrents already at room temperature under irradiation of the samples with photons even at energies just below the fundamental optical gap. Photoconductivity increases strongly at low temperature. Intense thermally stimulated current peaks between 15 and 100 K are probably due to the presence of shallow hole traps and polaronic centres. The obtained results are compared to past observations in pure KTaO3 and KTaO3:Li