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

Albert Juma, Ilona Oja Acik, Arvo Mere, Malle Krunks

Research output: Contribution to journalArticle

2 Citations (Scopus)

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 °C. Anatase to rutile transformation started after annealing at 800 °C, and at 950 °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 °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.

Original languageEnglish
Article number359
JournalApplied Physics A: Materials Science and Processing
Volume122
Issue number4
DOIs
Publication statusPublished - Apr 1 2016

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Dielectric relaxation
Annealing
Thin films
Titanium dioxide
Electric properties
Microstructure
Spray pyrolysis
Bias voltage
Densification
Electric space charge
Leakage currents
Temperature
Permittivity
Spectroscopy
Substrates
Air
titanium dioxide

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)

Cite this

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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 °C. Anatase to rutile transformation started after annealing at 800 °C, and at 950 °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 °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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Dielectric relaxation and conduction mechanisms in sprayed TiO2 thin films as a function of the annealing temperature. / Juma, Albert; Acik, Ilona Oja; Mere, Arvo; Krunks, Malle.

In: Applied Physics A: Materials Science and Processing, Vol. 122, No. 4, 359, 01.04.2016.

Research output: Contribution to journalArticle

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AB - 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 °C. Anatase to rutile transformation started after annealing at 800 °C, and at 950 °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 °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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