Gate-All-Around Nanowire Junctionless Transistor-Based Hydrogen Gas Sensor

Abstract

This paper reports on the detection of hydrogen (H ₂ ) gas by utilizing a gate-all-around nanowire (NW) junctionless (JL) transistor as a sensor. The effects of temperature and pressure are considered in the transduction process through a change in gate workfunction of palladium (Pd) gate after exposure to H ₂ gas. The analysis is performed through TCAD simulations, and an analytical model is developed in the subthreshold regime of device operation at a relatively low drain bias of 0.5 V. The performance of the NW JL transistor gas sensor is evaluated through the OFF-current-based sensitivity (S _I ) and sensitivity based on threshold voltage shift (S _V ). The analytical model developed for S _I and S _V shows a very good consistency with simulation data. The anomalous behavior of threshold voltage with temperature in the NW JL transistor under the influence of H ₂ gas is analyzed in detail. This paper predominantly focuses on utilizing the NW JL transistor for low-power gas sensing, specifically at low pressures (10 ^-15 -10 ^-10 torr), for temperatures ranging from 250 to 450 K. Insights into physical mechanisms within the device due to the transduction process are highlighted for optimum sensing.