Modeling and Simulation Characteristics of a Highly-Sensitive Stack-Engineered Junctionless Accumulation Nanowire FET for PH₃ Gas Detector

Abstract

A stack-engineered junctionless accumulation nanowire FET (SE-JAM-NW FET) is proposed for low-power and high-sensitivity phosphine (PH3) gas detection applications. Compared to a standard nanowire field-effect transistor, SE-JAM-NW FET is used at nanoscale dimensions because of its inherent benefits, including low cost, improved portability, low Off- state current, and increased On-state current with low power consumption. To implement SE-JAM-NW FET as a phosphine gas sensor, four catalytic metals, Platinum (Pt), Rhodium (Rh), Iridium (Ir), and Palladium (Pd) have been employed as gate electrodes. In designing a gas sensor, various electric parameters like potential, electron concentration, recombination rate, and electron velocity were evaluated for PH3 gas detection. To forecast the sensor's response, analog characteristics like change in drain current, transconductance, and output conductance were simulated for different catalytic metal work functions (200, 150, 100, and 50 meV) at the gate electrode. The variation in On-state current to Off-state current ratio (IOn/IOff), On-state current (IOn), and subthreshold leakage current (IOff) for sensing gas molecules have been used to quantify sensitivity. Effects of silicon pillar-based radius variation and channel length variation on the sensitivity-based parameters were also investigated. Each catalytic metal exhibits improved sensitivity with increased channel length and decreased radius.