Dielectric relaxation and conduction mechanisms in sprayed TiO2 thin films as a function of the annealing temperature

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Author list: Juma A, Acik IO, Mere A, Krunks M

Publisher: Springer

Place: NEW YORK

Publication year: 2016

Journal: Applied Physics A: Materials Science and Processing (0947-8396)

Journal acronym: APPL PHYS A-MATER

Volume number: 122

Issue number: 4

Number of pages: 6

ISSN: 0947-8396

eISSN: 1432-0630

Languages: English-Great Britain (EN-GB)

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Abstract

The electrical properties of TiO2 thin films deposited by chemical spray pyrolysis onto Si substrates were investigated in the metal-oxide-semiconductor (MOS) configuration using current-voltage characteristics and impedance spectroscopy. The electrical properties were analyzed in relation to the changes in microstructure induced during annealing in air up to a temperature of 950 degrees C. Anatase to rutile transformation started after annealing at 800 degrees C, and at 950 degrees C, only the rutile phase was present. The dielectric relaxation strongly depended upon the microstructure of TiO2 with the dielectric constant for the anatase phase between 45 and 50 and that for the rutile phase 123. Leakage current was reduced by three orders of magnitude after annealing at 700 degrees C due to the densification of the TiO2 film. A double-logarithmic plot of the current-voltage characteristics showed a linear relationship below 0.12 V consistent with Ohmic conduction, while space-charge- limited conduction mechanism as described by Child's law dominated for bias voltages above 0.12 V.

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