Junction-Tuned SnO₂ Nanowires and Their Sensing Properties

Abstract

On the basis of a selective growth of SnO2 nanowires by the vapor–liquid–solid growth method, networked SnO2 nanowire sensors were fabricated. Then, their sensing properties were systematically investigated in terms of NO2. The density of junctions was controlled by altering the spacing of the patterned-interdigital electrodes (PIEs), on which SnO2 nanowires selectively grew and touched the nanowires grown on neighboring PIEs, eventually producing junctions. The sensing mechanism was attributed to the change not only in the width of the space charge region along the length direction of each nanowire but also in the height of the built-in potential at the junctions during adsorption and desorption of gaseous species. Narrower spacings of PIEs led to an increasing the density of junctions projected to the plane and, consequently, superior properties for gas sensing. Importantly, a general principle to prepare networked nanowires of superior sensing capabilities was suggested from the point of view of nanowire shape and electrode configuration.

Synthesis and Sensing Properties of Pd Nanoparticle-Functionalized SnO2Nanowires

“…The overall effect reduces the conductance, which ultimately lowers the response time and enhances the sensitivity. Another possibility is that the Pd nanoparticles induce catalytic effects and dissociate the NO 2 into ions or neutral chemical species, such as NO, O, NO 2 -, NO + and NO - [14][15][16][17]. These chemical species tend to capture the electrons in SnO 2 nanowires, enhancing the sensing properties.…”

Fabrication and properties of trench-structured networked SnO2 nanowire gas sensors

“…During the VLS growth of the SnO 2 nanowires, N 2 and O 2 flowed through the quartz tube at rates of 300 standard cubic centimeters per minute (sccm) and 10 sccm, respectively. A more detailed experimental procedure for synthesizing the selectively grown networked SnO 2 nanowires is described in our earlier publications [18,19].…”

“…To circumvent the shortcomings caused by the use of single nanowire in gas sensors, on-chip networked nanowire sensors have been attempted by some research groups [12][13][14][15][16] including the present authors [17,18], in which multiple nanowires were involved in the sensing process through a simple fabrication process. In our earlier studies [17,18], networked nanowire sensors were successfully fabricated based on the selective growth of SnO 2 and ZnO nanowires * Corresponding author. Tel.…”

“…As a general rule, a greater number of junctions in multiplenetworked sensors is likely to show better sensing capabilities in terms of sensitivity and reliability [18]. Up to the present, multiplenetworked sensors have been realized only on planar surfaces.…”

Formaldehyde sensing mechanism of SnO2 nanowires grown on-chip by sputtering techniques

“…In order to have the advantages of nanomaterials but applicable at commercial level, some works have been focused on developing on-chip nanowire growing procedures. 6,7 The methods reported in literature are usually based on thermal evaporation and chemical vapour deposition techniques. [8][9][10] The source material is a metallic powder placed in an alumina crucible inside a horizontal quartz tube furnace.…”