Abstract
In this work, we isolate individual wurtzite InAs nanowires and fabricate electrical contacts at both ends, exploiting the single nanostructures as building blocks to realize two different architectures of conductometric sensors: (a) the nanowire is drop-casted onto—supported by—a SiO2/Si substrate, and (b) the nanowire is suspended at approximately 250 nm from the substrate. We test the source-drain current upon changes in the concentration of humidity, ethanol, and NO2, using synthetic air as a gas carrier, moving a step forward towards mimicking operational environmental conditions. The supported architecture shows higher response in the mid humidity range (50% relative humidity), with shorter response and recovery times and lower detection limit with respect to the suspended nanowire. These experimental pieces of evidence indicate a minor role of the InAs/SiO2 contact area; hence, there is no need for suspended nanostructures to improve the sensing performance. Moreover, the sensing capability of single InAs nanowires for detection of NO2 and ethanol in the ambient atmosphere is reported and discussed.
Highlights
The development of innovative sensors for the detection of chemical and biological species is a crucial ingredient for real advancements in many fields across physical, engineering and life sciences, including healthcare [1,2,3], food safety [4,5], environmental protection [6,7], agriculture [8,9], and security [10]
The comparison between the performances of suspended and supported nanowire-based devices revealed that the availability of a slightly larger nanowire surface for gas interaction in suspended nanowire, as well as the ideal geometry for gas flowing around the nanowires, are not reflected in higher sensor response, while they are linked to an increase of response and recovery times
We have reported the use of individual InAs nanowires for the realization of conductometric sensors for the detection of different chemical species diluted in synthetic air
Summary
The development of innovative sensors for the detection of chemical and biological species is a crucial ingredient for real advancements in many fields across physical, engineering and life sciences, including healthcare [1,2,3], food safety [4,5], environmental protection [6,7], agriculture [8,9], and security [10]. The advent of nanomaterials paved the way to advanced sensor performances, and the continuous progress in nanoscience and nanotechnology holds the promise for large implications in innovative and more performing detection systems [11,12,13,14]. In this context, nanowires (NWs) are emerging as promising platforms for the development of ultrasensitive sensors for the direct detection of biological and chemical species [15,16,17,18]. Different NW materials [20,22,23,24], sensed molecules [21,25,26,27], device architectures [28,29,30], and signal transduction methods [31] are currently being studied
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