Study of the oxygen vacancies changes in SnO2 polycrystalline thick films using impedance and photoemission spectroscopies

Changes in the concentration of oxygen vacancies within the grains of polycrystalline SnO2, due to different atmosphere exposures, were detected using impedance and photoemission spectroscopies. From measured capacitance values, variations of the potential barrier widths could be determined. It is s...

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Bibliographic Details
Published in:Journal of applied physics 2014-11, Vol.116 (19)
Main Authors: Schipani, F., Ponce, M. A., Joanni, E., Williams, F. J., Aldao, C. M.
Format: Article
Language:English
Subjects:
Applied physics
Capacitance
Gas sensors
Grains
Impedance
Oxidation
Oxygen
Photoelectric emission
Polycrystals
Potential barriers
Thick films
Tin dioxide
Vacancies
X ray spectra
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Summary:Changes in the concentration of oxygen vacancies within the grains of polycrystalline SnO2, due to different atmosphere exposures, were detected using impedance and photoemission spectroscopies. From measured capacitance values, variations of the potential barrier widths could be determined. It is shown that under the presence of an oxygen rich atmosphere, at relatively low temperature, the width of intergranular potential barriers increase to the point that grains become completely depleted of carriers. With subsequent exposure to vacuum, capacitance adopts a higher value, indicative of intergranular barriers and quasi-neutral regions at the center of the grains. X-ray and ultraviolet photoemission spectroscopy measurements showed that SnO2 samples treated in oxidizing or reducing environments have similar barrier heights and different work functions. Results are especially relevant in the study of mechanisms responsible for metal oxide gas sensing.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4902150