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Scaling of flat band potential and dielectric constant as a function of Ta concentration in Ta-TiO2 epitaxial films

Authors :
Y. L. Zhao
A. Roy Barman
S. Dhar
A. Annadi
M. Motapothula
Jinghao Wang
Haibin Su
M. Breese
T. Venkatesan
Q. Wang
Source :
AIP Advances, Vol 1, Iss 2, Pp 022151-022151-9 (2011)
Publication Year :
2011
Publisher :
AIP Publishing LLC, 2011.

Abstract

Electrochemical impedance spectroscopy measurements of pulsed laser deposited single crystal anatase TiO2 thin films with various concentrations of Ta substituting for Ti were carried out. The qualities of the films were characterized by X-ray diffraction and Rutherford back scattering-channeling measurements. UV-visible measurements show a systematic increase of the bandgap with Ta incorporation. Corresponding Mott-Schottky plot was applied to obtain a continuous shift of the flat band potential with increasing free charge carrier (provided by Ta) concentration. This was verified theoretically by ab initio calculation which shows that extra Ta d-electrons occupy Ti t2g orbital with increasing Ta concentration, thereby pushing up the Fermi level. The Mott-Schottky results were consistent when compared with Hall effect and temperature dependent resistivity measurements. From the measured deviation of carrier densities from Hall and Mott-Schottky measurements we have estimated the static dielectric constant of the TiO2 as a function of Ta incorporation, not possible from capacitive measurements.

Subjects

Subjects :
Physics
QC1-999

Details

Language :
English
ISSN :
21583226
Volume :
1
Issue :
2
Database :
Directory of Open Access Journals
Journal :
AIP Advances
Publication Type :
Academic Journal
Accession number :
edsdoj.633aa8945f874fa287c2072d57633342
Document Type :
article
Full Text :
https://doi.org/10.1063/1.3609927