Investigations of conduction mechanism in Cr sub(2)O sub(3) gas sensing thick films by ac impedance spectroscopy and work function changes measurements

• Published in: Sensors and actuators. B, Chemical Vol. 133; no. 1; pp. 78 - 83
• Main Authors: Pokhrel, S, Simion, CE, Quemener, V, Barsan, N, Weimar, U
• Format: Journal Article
• Language: English
• Published: 28.07.2008
• ISSN: 0925-4005
• DOI: 10.1016/j.snb.2008.01.054

This paper investigates the conduction mechanism in Cr sub(2)O sub(3) gas sensing thick films. A citrate combustion method was used for the preparation of the metal oxide and ethanol vapour as a test gas. The manner in which surface reactions induced electrical changes are affecting the sensor signals inputs was explored by simultaneous dc and work function changes (Kelvin probe method). The identification of the contributions to conduction of the different sensing layer elements was made possible by ac impedance spectroscopy measurements. A conduction model, which qualitatively explains the experimental findings, was elaborated on the basis of the acquired experimental data and the information provided in literature. The model validity should apply, besides Cr sub(2)O sub(3), to all p-type metal oxides used as gas sensitive materials.