The role of hydrogen in the persistent photoconductivity of SrTiO3

ORAL

Abstract

Strontium titanate (STO) is a perovskite oxide with an indirect bandgap of 3.25 eV at room temperature. It has been often used as substrate to grow other materials, and it is the basis of widely reported perovskite heterostructures that show high-density two-dimensional electron gas. Recently, an extremely long persistent photoconductivity (PPC) at room temperature has been observed in annealed strontium titanate single crystals upon illumination with sub-gap light [M. C. Tarun, F. A. Selim, and M. D. McCluskey,Phys. Rev. Letters, 111, 187403 (2013)]. Annealed studies indicate the importance of hydrogen impurities as well as oxygen vacancies to induce PPC. We use electronic structure calculations based on density functional theory (DFT) to investigate possible mechanisms behind the PPC effect. We present results of defect formation energies, defect-related absorption, and defect migration barriers, in an attempt to identify the defect associated with the observed PPC in STO. The results are combined to explain the experimental observations, and we further generalize the model to predict similar effects in other oxide like TiO2 and BaTiO3.

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Presenters

  • Zhiqiang Zhang

    Physics and Astronomy, University of Delaware

Authors

  • Zhiqiang Zhang

    Physics and Astronomy, University of Delaware

  • Anderson Janotti

    Department of Material science and Engineering, University of Delaware, Department of Physics & Astronomy, University of Delaware, Materials Science and Engineering, University of Delaware, University of Delaware, Department of Materials Science & Engineering, University of Delaware, Department of Materials Science and Engineering, University of Delaware