Atomic control and characterization of surface defect states of TiO(sub 2) terminated SrTiO(sub 3) single crystals.
By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO{sub 2} terminated surfaces of SrTiO{sub 3} 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 Ti{sup 3+} 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 Ti{sup 3+} 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.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 937409
- Report Number(s):
- ANL/XSD/JA-61626; APPLAB; TRN: US0805784
- Journal Information:
- Appl. Phys. Lett., Vol. 93, Issue Aug. 11, 2008; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- ENGLISH
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