Dresden 2020 – scientific programme
The DPG Spring Meeting in Dresden had to be cancelled! Read more ...
Parts | Days | Selection | Search | Updates | Downloads | Help
KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 9: Focus: Polar oxide crystals and solid solutions
KFM 9.7: Talk
Wednesday, March 18, 2020, 11:40–12:00, TOE 317
Photoconductivity of strontium barium niobate revisited: spectral features, long-term relaxation, current-voltage hysteresis — •Elke Beyreuther1, Julius Ratzenberger1, Liudmila I. Ivleva2, Pavel A. Lykov2, and Lukas M. Eng1,3 — 1Institute of Applied Physics, Technische Universität Dresden, 01062 Dresden, Germany — 2Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow, Russia — 3Cluster of Excellence 2147 – Complexity and Topology in Quantum Matter (ct.qmat)
Here, we report on the large photoconductive response (PCR) of strontium barium niobate (Sr0.61Ba0.39Nb2O6, SBN61) single-crystals grown by the modified Stepanov technique. We analyzed the PCR for both z- and x-cut SBN61 samples, using two different electrical wiring setups for each, by gradually varying the intensity and spectral composition of the incident photons. The crystals show a pronounced PCR already under diffuse daylight. Apart from a huge resistance decrease by three orders of magnitude upon super-bandgap illumination (370 nm), we observe in all four samples (i) distinct spectral features upon sub-bandgap excitation (800-390 nm) that clearly hint towards in-gap states beyond the one- and two-center models discussed in conjunction with doped SBN61 so far, as well as (ii) an extremely slow long-term relaxation for both light-on and light-off transients in the range of hours (after sub-bandgap excitation) and days (after super-bandgap excitation). Moreover, a strong phototunable I-V hysteresis (tested with 500-nm and 380-nm illumination) along the polar axis of the z-cut sample is measured.