The electronic structure of lightly Nb-doped (Formula presented) has been investigated using high resolution x-ray absorption spectroscopy (XAS). Below the O (Formula presented) threshold, XAS spectra show two features due to empty states whose energy positions match with those of the (Formula presented) photoemission spectra in the band gap energy region of the parent undoped (Formula presented) Similar features are also observed in lightly La-doped (Formula presented) These features exhibit systematic temperature dependence, which is well explained by the Fermi-Dirac distribution function. This indicates that the two features in the band gap are real bulk states such as simple donor states.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2000
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics