Structural Properties and Sensing Performance of CeYxOy Sensing Films for Electrolyte-Insulator-Semiconductor pH Sensors

Tung Ming Pan*, Chih Wei Wang, Ching Yi Chen

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

11 Scopus citations

Abstract

In this study we developed CeYx Oy sensing membranes displaying super-Nernstian pH-sensitivity for use in electrolyte-insulator-semiconductor (EIS) pH sensors. We examined the effect of thermal annealing on the structural properties and sensing characteristics of the CeYx Oy sensing membranes deposited through reactive co-sputtering onto Si substrates. X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy revealed the structural, morphological, and chemical features, respectively, of the CeYx Oy films after their annealing at 600-900 °C. Among the tested systems, the CeYx Oy EIS device prepared with annealing at 800 °C exhibited the highest sensitivity (78.15 mV/pH), the lowest hysteresis voltage (1.4 mV), and the lowest drift rate (0.85 mV/h). Presumably, these annealing conditions optimized the stoichiometry of (CeY)O2 in the film and its surface roughness while suppressing silicate formation at the CeYx Oy-Si interface. We attribute the super-Nernstian pH-sensitivity to the incorporation of Y ions in the Ce framework, thereby decreasing the oxidation state Ce (Ce4+ → Ce3+) and resulting in less than one electron transferred per proton in the redox reaction.

Original languageEnglish
Article number2945
JournalScientific Reports
Volume7
Issue number1
DOIs
StatePublished - 01 12 2017

Bibliographical note

Publisher Copyright:
© The Author(s) 2017.

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