Analytical Modelling of Dielectric Modulated Negative Capacitance
MoS2-FET for Biosensor Application
Abstract
In this paper, a dielectric modulated negative capacitance
(NC)-MoS2 field effect transistor (FET)-based biosensor
is proposed for label-free detection of biomolecules such as enzymes,
proteins, DNA, etc. Various reports present experimental demonstration
and modelling of NC-MoS2 FET, but it is never utilized
as a dielectric modulated biosensor. Therefore, in this work, the
modelling, characterization and sensitivity analysis of dielectric
modulated NC-MoS2 FET is focussed. For immobilization of
biomolecules, a nanocavity is formed below the gate by etching some
portion of the gate oxide material. The immobilization of biomolecules
in the cavity leads to a variation of different electrostatic properties
such as surface potential, threshold voltage, drain current, and
subthreshold-swing (SS) which can be utilized as sensing parameters. An
analytical model for the proposed biosensor is also developed in the
subthreshold region by considering the properties of two-dimensional
(2D) ferroelectric materials and benchmarked with TCAD device
simulations. The effect of change of gate length and doping
concentration on different electrical properties is also analysed to
estimate the optimum value of channel doping. The results prove that the
proposed device can be used for next-generation low power label-free
biosensor which shows enhanced sensitivity as compared to traditional
FET-based biosensors.