Design and Fabrication of Electrostatically Formed Nanowire Gas Sensors With Integrated Heaters

This work reports on the design and fabrication of planar gas sensors with membrane structure to allow in-situ heating capabilities crucial for enhancing gas sensing performances. The sensors are virtual nanowire field-effect transistor (FET) type devices, referred to as electrostatically formed nanowire (EFN) sensors. This work describes the design, fabrication, and performance of a 2 mm X 2 mm chip with
$850 ~\mu \text{m}$
diameter,
$3.5 ~\mu \text{m}$
thick membrane. The design has been analyzed using finite element simulations (FEM) and verified experimentally. The thermal efficiency of the heated membrane is found to be 10 mW to reach 400 °C, which is better than most of the reported membrane-based sensors. To improve sensitivity and for broader functionality, the sensing surface, unlike reported in most designs, is at the bottom of the membrane. The technology allows system on chip (SoC) integration and further can be used for the fabrication of handheld battery-operated gas detectors. [2021-0248]