Dynamic Range\nEnhancement Using the Electrostatically\nFormed Nanowire Sensor

Abstract

The\nevolution of nanotechnology based sensors has enabled detection\nof ultra-low-level concentrations of target species owing to their\nhigh aspect ratio. However, these sensors have a limited dynamic range\nat room temperature characterized by saturation in the sensor response\nfollowing certain concentration exposure. In this work, we show that\nthe dynamic range towards a target gas can be significantly enhanced\nusing the electrostatically formed nanowire sensor. The size and shape\nof the nanowire conducting channel are defined and tuned by controlling\nthe bias applied to the surrounding gates. The nanowires thus formed\nvary in their response, detection limit, and dynamic range for a given\ntarget gas exposure depending on its size and shape. By electrostatically\ntuning to the appropriate nanowire, we can not only enhance the sensor\nresponse in the low concentration regime, but also broaden the overall\ndynamic range capacity using a single sensor. It is demonstrated that\nthe sensor is capable of detecting ∼26–2030 ppm ethanol\nand ∼40–2800 ppm of acetone efficiently with reasonably\nhigh response (≥20%) throughout the whole range. The broad\ndynamic range concept is also demonstrated using scanning gate microscopy\nmeasurements of the device. This represents the first nanotechnology-inspired\nwork towards tunable dynamic range of a sensor using a single electronic\ndevice.