MS&E Colloquium - Prof. Yigal Komem
Date: January 23, 2009 from 2:00 pm to 3:00 pm EST
Location: Columbia University
Morningside Campus
214 S. W. Mudd Building
Contact: For further information regarding this event, please contact Chad Gurley by sending email to cg2029@columbia.edu .
Info: Click Here to Visit Website.
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Titanium Oxide Thin Film Gas Sensors

Prof. Yigal Komem                       

Faculty of Materials Engineering
Technion - Israel Institute of Technology

There is a growing interest in gas sensors devices based on metal-oxide thin films that enable gas recognition for potential "electronic micro-nose" applications. In metal-oxides the chemisorbed oxygen species on the surface play a predominant role of surface receptors that mediate charge transfer interactions between the ambient gas molecules and the metal-oxide sensing layers. These interactions are eventually transduced to an electrical signal that forms the sensor response, that is, a conductivity change. TiO2 thin polycrystalline films were studied as a prosper material for gas sensors devices due to their electrical conductance sensitivity to concentrations of analytes in the ambient atmosphere and compatibility to silicon technology. The microstructure of metal oxides films, namely grain size and grain boundaries, has a significant role in the sensing mechanism. Sensing properties of TiO2 films, deposited by RF sputtering, exposed to oxygen and CO will be shown. However, such films are dense, have grain size limited to their thickness and small surface-to-volume ratio. The novel method developed by James. S. Im, that utilizes pulsed excimer laser irradiation (PLI) to process Si and metal films to obtain polycrystalline structure with a desired grain size, was first applied successfully to produce titanium oxide films in a controlled manner with varied grain size. First results of the sensing properties of PLI-processed TiO2 films exposed to H2 and NO2 will be shown.