Structural Phase Transition and Photo-Charge Carrier Transport in SrTiO₃

The effect of the antiferrodistorsive phase transition observed at ∼ 105 K on the photo-carriers transport and band structure of nominally pure SrTiO₃ single crystals was investigated. Simultaneously the ab-initio analysis based on the DFT-HF hybrid approach was performed in order to elucidate the atomic and electronic structure changes. It was found that the structural transition play a minor role in photo-charge transport. However, in highly resistive specimens at low UV-light intensities or under visible-light, 514 nm excitation, weak photoconductivity features are observed in the transition region. Besides, in this region the temperature maximum was found for the photoconductivity spectra. Experimental results are discussed and agree well with theoretical predictions.

Keywords:

• SrTiO₃
• phototransport properties
• quantum paraelectrics

Acknowledgments

This work was supported by Project 1QS100100563 of the AS CR, the Program of he Presidium RAS “Low dimensional quantum structures” and by Italian Grant FIRB RBNE01KZ94.

Paper originally presented at IMF-11, Iguassu Falls, Brazil, September 5–9, 2005