SrTiO{sub 3}(001)-({radical}(5)x{radical}(5))-R26.6 deg. reconstruction: A surface resulting from phase separation in a reducing environment

Journal Article · Tue May 15 00:00:00 EDT 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.75.205429· OSTI ID:21045883

Newell, David T; Silly, Fabien; Castell, Martin R ^[1]; Harrison, Alastair ^[2]

---

1. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)
2. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom)

Scanning tunneling microscopy (STM) was used to produce atomic resolution images of the Nb-doped SrTiO{sub 3}(001)-({radical}(5)x{radical}(5))-R26.6 deg. reconstruction and its precursor surfaces. Low-energy electron diffraction was used to identify the surface structure in combination with the STM imaging. The ({radical}(5)x{radical}(5))-R26.6 deg. reconstruction was observed growing as an adlayer on top of the underlying terraces. The formation of this structure could routinely be detected by an increase in the crystal's electrical conductivity during ultrahigh vacuum (UHV) annealing at 1300 deg. C. This rise in conductivity occurs due to significant reduction of the crystal. Scanning electron microscopy (SEM) on these samples showed small islands with a rectangular base separated by flat regions. Auger electron spectroscopy showed titanium enrichment, and strontium and oxygen depletion of the surface region. The islands seen in the SEM images are TiO crystals, as reported by S. B. Lee et al. [Ultramicroscopy 104, 30 (2005)]. The flat regions between the islands are composed of a Sr adlayer on the surface that is consistent with the ({radical}(5)x{radical}(5))-R26.6 deg. adatom model of Kubo and Nazoye [Phys. Rev. Lett. 86, 1801 (2001)]. We propose that the TiO islands and the ({radical}(5)x{radical}(5))-R26.6 deg. Sr adlayer reconstruction form due to phase separation in the surface region of the crystal. This phase separation is driven by oxygen depletion which occurs during high-temperature UHV annealing of the sample.

• OSTI ID: 21045883
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 75, Issue 20; Other Information: DOI: 10.1103/PhysRevB.75.205429; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
ANNEALING
AUGER ELECTRON SPECTROSCOPY
CRYSTALS
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRON DIFFRACTION
FERROELECTRIC MATERIALS
LAYERS
NEODYMIUM
OXYGEN
SCANNING ELECTRON MICROSCOPY
SCANNING TUNNELING MICROSCOPY
STRONTIUM
STRONTIUM TITANATES
SURFACES
TEMPERATURE RANGE 0400-1000 K
THIN FILMS
TITANIUM
TITANIUM OXIDES