Atomic control and characterization of surface defect states of TiO 2 terminated SrTiO3 single crystals

M. Kareev, S. Prosandeev, J. Liu, C. Gan, A. Kareev, J. W. Freeland, Min Xiao, J. Chakhalian

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Abstract

By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO2 terminated surfaces of SrTiO3 single crystals with the morphology equivalent to that of the conventional wet-etch methods. By applying a combined power of photoluminescence (PL) spectroscopy, reflection high-energy electron diffraction, atomic force microscopy imaging, and soft x-ray absorption (XAS), we were able to identify and monitor the complex evolution of oxygen defect states and Ti valency at the surface and near-surface layers. Our experiments revealed a high level of local defects resulting in the presence of the Ti3+ states at the surface. We have developed a method to control the defect states capable of a marked reduction of the defect concentration. We have demonstrated that the PL and XAS are able to distinguish the surface-related Ti3+ states from oxygen vacancies trapping charge transfer vibronic excitons that define the PL intensity. The experimental findings will have important implications for the growth of high-quality ultrathin complex oxide heterostructures.

Original languageEnglish (US)
Article number061909
JournalApplied Physics Letters
Volume93
Issue number6
DOIs
StatePublished - 2008

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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