Modeling and Simulation Investigation of Sensitivity of Symmetric Split Gate Junctionless FET for Biosensing Application

Abstract

In this paper, an analytical model has been developed for a split gate junctionless (JL) MOSFET, which works as a bio-transistor to detect the analytes (biomolecules), such as protein, DNA, enzyme, cell, and so on, using the dielectric-modulation technique. We have also studied the neutralization of charged analytes when charge reduction due to drying out. The analytical model has been investigated by solving 2-D Poisson’s equation. For the validation of analytical results, a split gate JL MOSFET has been virtually fabricated through sprocess and the electrostatic properties of device simulated by sdevice tools of the “Sentaurus” device simulator. For the bio-species immobilization, an underlap region also known as open cavity is formed in the device through etching oxide material and gate material from the middle of the channel. The electrostatic properties of device, such as surface potential, threshold voltage, drain current, and sensitivity, get affected by the immobilization of analytes at the SiO2 layer (which acts as an adhesion layer in the cavity region). The change in the threshold voltage and transfer characteristics of the device is pondered as the sensing metric to detect the bio-targets under dry environment.