Investigation on the variation effect of gate work function on \(N^+\) pocket-doped junctionless vertical tunneling FETs

Abstract

In this work, a novel \(N^{+}\) pocket-doped gate stack junctionless vertical tunnel field-effect transistor is proposed for gas sensing applications. For better gate controllability over the channel potential and enhanced tunneling area, the conventional gate oxide is replaced with a high-k (HfO₂) gate oxide in stack with a SiO₂. \(N^{+}\) SiGe pocket at the source–channel interface, which improves the band-to-band tunneling rate because of its lower bandgap compared to silicon. Work function modulation of the catalytic metal gate on exposure to gas molecules is used as the detection mechanism. In this work, silver, palladium and cobalt gate electrodes are used for sensing oxygen, hydrogen and ammonia gases, respectively. The Silvaco ATLAS TCAD tool is used for numerical simulation of the proposed device. Performance of the device is evaluated by analyzing the sensitivity of the device for temperatures ranging from 100K to 300K and pressures from \(10^{-14}\) Torr to \(10^{-10}\) Torr. Due to its low power consumption, good thermal stability and improved sensitivity, the proposed gas sensor finds applications in a wide variety of fields like electronic noses and automobiles.