Electrical Characterisation of a Low-Density Layer of SnO Nanowires Deposited on a Set of Parallel Pt Electrodes
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1080-O15-01
Electrical Characterisation of a Low-Density Layer of SnO Nanowires Deposited on a Set of Parallel Pt Electrodes Joachim Goschnick1, Ilia Kiselev1, Victor Sysoev2, and Thomas Schneider1 1 Institute of Microstructure Technology, Forschungszentrum Karlsruhe, Hermann-vonHelmholtz-Platz 1, Karlsruhe, D-76344, Germany 2 Physics Department, Saratov State Technical University, Polytechnicheskaya 77, Saratov, 410054, Russian Federation ABSTRACT Low-density layers of SnO2 nanowires were produced using the vapor solid method and dry-pressed onto surface-oxidized Si-substrates equipped with a set of 39 parallel Pt-electrodes. Current-Voltage (I-V) characteristics of the segments between the electrodes were measured in ambient air at a substrate temperature of 300°C. Statistical analysis of the 38 I-V characteristics allows drawing conclusions, that only Schottky contacts between large nanowires and electrodes are significant for conductometry, and that they have very similar barrier characteristics. The statistical approach and its advantages are demonstrated. The clarity obtained concerning the roles of different resistivity mechanisms involved enables predictions of the nanowire net device behavior in applications, which is demonstrated on an instance of long-term stability examination of gas sensor arrays. INTRODUCTION As devices equipped with nanowires gain more and more practical relevance, the urgency rises to switch from hand-made depositions of nanowires onto carrier structures to more simple deposition procedures, which are suitable for standardization. The resulting devices are naturally more liable to statistical characterization, and this characterization brings out much more than just the necessary assessment of parameter variation level. The correlation and dispersion analysis allows separation of the parameters which mask each other if single objects are examined. By the present investigation, the statistical approach shows 1) which fraction of nanowires of available range plays the major role in conductivity, and therefore sensitivity; 2) which type of the electrical resistance is essential for practical applications; 3) in what extent the conclusions from 1) and 2) are persistent through the set of nanowire bearing segments (or generalizing – among nanowire devices of the same type). Using a conductivity measuring device without sufficient knowledge of its I-V characteristic can result in a wrong belief about the operation of a device and therefore in wrong expectations and erroneous developments. As an example, the present case of usage of nanowire net as the sensing element in gas sensor arrays can be considered. Based on the measurements with single nanowires [1], which demonstrated a clear ohmic behavior, and on the conception of a nanowire as almost perfect crystal, we have expected much better stability although less sensitivity of the constructed nanowire electronic nose, than it turned to be in reality [2]. Indeed, several days after production a SnO2 nanowire demonstrates a relatively low
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