Tel Aviv University,
Keywords: nanowire, sensor response, sensor selectivity, chemical sensor, gas sensor, volatile organic compounds
Summary:J. Hayon, N. Mahapatra, H. Henning, K. Shimanovich and Y. Rosenwaks The need for reliable and miniature gas sensors, as a means of alert against the dispersion of hazardous materials (whether as a result of e.g. an industrial accident, a terror event or even environmental circumstances) does exist and the importance of immediate on-the -spot detection increases continuously. A new generation of integrated sensors e.g. in wearables or personal assistants (e.g. smartphones) is evolving as elementary building blocks for the internet of things (IoT). In this work, we developed and tested robust nanoscale gas sensors suitable for mass production based on the electrostatically formed nanowire (EFN) concept. The gas sensor is based on the electrostatically formed nanowire (EFN) device, which is nano-scale size channel of a transistor induced by four biasing gates. The gas sensing is achieved by analyte molecules that change the channel surface potential and as a result modulate the drain-source current. Gas selectivity is achieved by a novel concept termed “electrostatic selectivity” that combines device surface electric fields with pattern recognition algorithms. It is based on the EFN surface fringing electric fields, which were found to have a very pronounced effect on the adsorption of analyte gas molecules. This allows tailoring chemical sensor sensitivity to specific target molecules. Adjusting the bias of the shallow p-n junctions in EFN chemical sensor, with an exposed top dielectric layer, allows tuning of the fringing electric field strength (0.5×107 to 2.5×107 V/m). We use this effect to develop a highly accurate selective and sensitive gas sensor.