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Nanoscaled p-type semiconductors for gas sensing : nanopowders, nanofilms, and nanowires

Title data

Sahner, Kathy ; Gouma, Perena ; Moos, Ralf:
Nanoscaled p-type semiconductors for gas sensing : nanopowders, nanofilms, and nanowires.
2006
Event: 2006 MRS Spring Meeting , 17.-21.04.2006 , San Francisco, Kalifornien.
(Conference item: Conference , Other Presentation type)

Abstract in another language

Since a high surface-to-volume ratio can be achieved using nanosized precursors, nanotechnology is of considerable interest in the field of semiconductor-based resistive gas sensing, where the underlying sensing mechanism generally is attributed to surface processes. The present contribution focuses on the application of nanoprecursors for p-type conducting perovskite strontium titanate ferrate, which is known for its good hydrocarbon sensitivity. Different methods of nanotechnology, i.e. sol-precipitation of nano-powders (particle size ~70 nm), electrospraying of nanocrystalline thin films (dense film, crystallites ~ 10 nm) and electrospinning of nanowires (fibre diameter: ~ 50 nm), are compared with respect to their sensitivity and specificity towards alcohol vapors and hydrocarbons such as propane. For each preparation technique, operating parameters have been optimized to assure good reproducibility of the samples. Unique feature of this study is that an identical precursor sol is prepared for each deposition method in order to assure a perfect comparability of the data. In addition, identical electrode structures, i.e. interdigitated Pt electrodes, are used. The different sensor devices are compared and contrasted to conventional micro-scaled thick film sensors (particle size ~1.2 μm). The Table presents the relative response R(analyte gas in air)/R(air) of the different sensors towards a variety of analyte gases at 400 °C. In each case, the use of nano-sized materials increases sensitivity towards methanol with best results for the sol precipitated nanopowder. In addition, the sensor response and recovery time are found to be very fast. Cross sensitivity towards ammonia can be reduced by applying a zeolite-based filter layer, which has been optimized in a complimentary study. After collecting additional data such as grain size, film density, and specific surface area, the gas test results are included in a model in order to describe the underlying gas mechanism. Based on the so-called diffusion-reaction process discussed in the literature for n-type semiconductor films, a correlation between microstructural parameters and underlying gas mechanism is developed, which aims at identifying the optimum microstructure for a given analyte gas.

Further data

Item Type: Conference item (Other)
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Faculties
Faculties > Faculty of Engineering Science > Chair Functional Materials
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Profile Fields
Profile Fields > Advanced Fields
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 17 Jun 2015 07:24
Last Modified: 06 Apr 2016 06:41
URI: https://eref.uni-bayreuth.de/id/eprint/14984