P1.3.17 Mechanistic Model for UV light-enhanced NO2 Sensing utilizing Ordered Mesoporous In2O3

14th International Meeting on Chemical Sensors - IMCS 2012
2012-05-20 - 2012-05-23
Nürnberg/Nuremberg, Germany
P1.3 Sensors Based on Optical Techniques
T. Wagner, M. Tiemann - Universität Paderborn, Naturwissenschaftliche Fakultät, Department Chemie (Germany), C. Kohl - Institute of Applied Physics, University of Giessen (Germany), S. Morandi - Department of Chemistry I.F.M. and N.I.S., Center of Excellence, University of Torino (Italy), C. Malagù - Department of Physics, University of Ferrara (Italy), N. Donato - Department of Matter Physics and Electronic Engineering, University of Messina (Italy), M. Latino - Department of Chemical Science and Technologies, University of Rome (Italy), G. Neri - Department of Industrial Chemistry and Materials Engineering, University of Messina (Italy)
978 - 980


Results on light-enhanced NO2 sensing utilizing ordered mesoporous In2O3 are presented and interpreted by means of a new sensing model for ordered mesoporous indium oxide (In2O3). This model aims to explain the drop in electronic resistance of n-type semiconducting In2O3 under UV light exposure as well as the light-enhanced sensing properties to oxidizing gases. Compared to the conventional double Schottky model the dominating factor for the resistance change is a change of oxygen vacancy donor states in the bulk phase due to photoreduction. Comparison of conductivity measurements with varying oxygen partial pressure for ordered mesoporous and nonstructured material shows an accumulative behavior in the case of the mesoporous material which can be related to faster photo reduction caused by the nanostructure. IR measurements reveal a donor level of 0.18 eV below the conduction band attributed to oxygen vacancies. The unique properties resulting from the structure allow lowtemperature sensing of NO2; especially the recovery times are significantly shorter for the mesoporous material.