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Optical properties and electronic structure of oxidized and reduced single-crystal strontium titanate

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Published/Copyright: January 11, 2022

Abstract

The measured optical and transport properties of singlecrystal SrTiO3 have been determined as a function of oxidation and reduction using spectroscopic ellipsometry, Hall and resistivity measurements. A decrease in the valence to conduction band transitions across the band gap, from O 2p to Ti 3d states, is observed by decreases in both the index of refraction and the extinction coefficient at the region of the band gap energy, in the ultraviolet region. This supports the model that oxygen nonstoichiometry depletes the O 2p densities of states in the top of the upper valence band, in agreement with previous photoemission studies. The degree of reduction decreases the band gap energy, calculated from the optical absorption coefficient spectra. The direct gap energy varies from 3.88 to 3.58 eV, and the indirect band gap energy ranging from 3.77 to 3.0 eV with increasing reduction. The resistivities of the samples decrease with increased reduction, yet free carrier densities are also found to decrease, suggesting an increase in electron mobility with reduction.


Dr. R. H. French DuPont Central Research E 356–384, Exp. Sta., Wilmington, DE 19880-0356, USA Tel.: +1 302 695 1319 Fax:+1 302 695 1664
Dedicated to Professor Dr. Dr. h. c. Manfred Rühle on the occasion of his 65th birthday *Presently at IBM Microelectronics

Funding statement: The authors would like to acknowledge M. F. Lemon for technical assistance with ellipsometry measurements and the comments and assistance of G. L. Tan with the manuscript. This work was partially supported under Department of Energy Office of Basic Energy Science DE-FG02-00Er45813, under National Science Foundation Award DMR-01062 in cooperation with European Union Contract G5RD-CT-2001-0586, and facilities use was supported by NSF MRSEC.

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Received: 2002-10-15
Published Online: 2022-01-11

© 2003 Carl Hanser Verlag, München

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. Editorial
  4. Articles/Aufsätze
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  6. Phase stability of Y + Gd co-doped zirconia
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  8. High-temperature oxidation of FeCrAl alloys: the effect of Mg incorporation into the alumina scale
  9. Nonlinear dielectric properties at oxide grain boundaries
  10. TEM observations of singular grain boundaries and their roughening transition in TiO2-excess BaTiO3
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  12. Microwave-induced crystallization of polysilazane-derived silicon carbonitride
  13. Schottky barrier formation in liquid-phase-sintered silicon carbide
  14. SrTiO3: a model electroceramic
  15. Optical properties and electronic structure of oxidized and reduced single-crystal strontium titanate
  16. Spreading of liquid Ag and Ag–Mo alloys on molybdenum substrates
  17. Nanoalloying in mixed AgmAun nanowires
  18. Never ending saga of a simple boundary
  19. Comparison of interfacial chemistry at Cu/α-alumina and Cu/γ-alumina interfaces
  20. Microstructure of Cu2O/Si interfaces, made by epitaxial electrodeposition
  21. Metal/oxide interfaces and their reaction with hydrogen
  22. Amorphous films at metal/ceramic interfaces
  23. Some thoughts on source monochromation and the implications for electron energy loss spectroscopy
  24. Determination of the contrast transfer function by analysing diffractograms of thin amorphous foils
  25. Progress in the preparation of cross-sectional TEM specimens by ion-beam thinning
  26. Quantification of interfacial segregation by analytical electron microscopy
  27. Quantification of elemental segregation to lath and grain boundaries in low-alloy steel by STEM X-ray mapping combined with the ζ-factor method
  28. Microstructure of Al/Ti metallization layers
  29. Connectivity of CSL grain boundaries and the role of deviations from exact coincidence
  30. Effect of laser shock processing on the microstructure and mechanical properties of pure Cu
  31. Growth and microstructure of iron nitride layers and pore formation in ε-Fe3N
  32. Phase diagram of the Al–Cu–Fe quasicrystal-forming alloy system
  33. Notifications/Mitteilungen
  34. Personal/Personelles
  35. Gesellschaftsnachricht
  36. International Conferences
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