Ionic-Liquid Gated Electrochemical Carbon Nanotube Transistor with High On-Off Ratio for Selective Gas Sensing

This is the authors' abstract. We don't add key points for this paper.

This work presents a gas sensor based on a field-effect transistor (FET) made of semiconducting single-walled carbon nanotubes gated by ionic liquids. Ionic liquids are used as: 1) gating electrolytes for the transistor on/off operation to enhance gas sensing sensitivity, and 2) functionalization to increase sensing selectivity. Prototype transistors have achieved high on/off ratios (106~107) with low operation voltages (threshold voltage ~ 0.3 V at source drain voltage of 50 mV). The sensitivity of NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> gas is enhanced by over 4 times through cation and anion variation in ionic liquids, while responses to different gases (NH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and CH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>) are observed by distinct patterns. By tuning the operation regime of the transistor through the gate bias voltage, a 5-fold increase in sensitivity is demonstrated for real-time room temperature detection of 100 ppm methane in nitrogen gas. As such, this new gas sensing method could open up new avenues for miniaturized electronic noses with high sensitivity and selectivity.