Electrical Characterization and Study of Current Drift Phenomena and Hysteresis Mechanism in Junctionless Ion-Sensitive Field-Effect Transistor

A comprehensive study of the drain current drift mechanism and hysteresis phenomena in fabricated p-channel junctionless ion-sensitive field-effect transistor (JL-ISFET) has been investigated for the first time. The current drift measurements have been performed through transient analysis of drain current, under different pH and liquid-gate bias (Vlg). Further, time-dependent gate-capacitance (CG) has also been analyzed to see the effect of hydroxyl ions (OH−) in the sensing film (Al2O3). The hysteresis has also been investigated for different pH loop (7 → 3 → 7 → 11 → 7 and 7 → 11 → 7 → 3 → 7) and times (960s, 1500s, and 1920s). It has been observed that the drift of JL-ISFET occurs because of chemical modification of the sensing film, due to OH−. The proposed device exhibits a threshold voltage sensitivity of 58.2 mV/pH that is near the Nernstian limit. Further, the hysteresis width and maximum drain current drift are measured as ∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sim $\end{document} 1.3 mV and 2.4 μ A (∼\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sim $\end{document} 75%), respectively.