Permittivity measurements in nanostructured TiO2 gas sensors

M.A. PONCE, R. PARRA, M.S. CASTRO, C.M. ALDAO, A. GIBERTI, C. MALAGU, M.C. CAROTTA, Y G. MARTINELLI

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE

WILEY-V C H VERLAG GMBH

Año: 2010 p. 1 - 5

1862-6300

Resistance and capacitance measurements, as a function offrequency, were carried out to analyze and model the electricalbehavior of undoped titanium dioxide (TiO2) films. The sensingmeasurements were carried out in a chamber with independenttemperature, pressure, gas composition, and flow rate control.With the aim of evaluating the electrical response of the sampleas a function of the surrounding atmosphere, a frequency rangeof 100 Hz–4MHz was used (vacuum or air at atmosphericpressure). The resistance and capacitance responses wereobtained with the help of impedance spectroscopy technique.The impedance response versus frequency allows the discriminationbetween grain-boundary capacitance (Cgb) and resistance(Rgb) contributions. A model, taking into account thepossible effects due to grain size is proposed in order to work outthe permittivity of the material.