Design and Investigation of Dielectrically Modulated Dual-Material Gate-Oxide-Stack Double-Gate TFET for Label-Free Detection of Biomolecules

This article investigates the applicability of dual-material gate-oxide-stack double-gate tunnel field effect transistor (DMGOSDG-TFET) as a biosensing element with the ability to assess the health parameters and disease onset. For this, employment of gate work-function engineering along with the gate-oxide-stack approach and asymmetrical doping at p+ source and n+ drain region are introduced for the first time to implement DMGOSDG-TFETbased biosensor. Also, a nanogap cavity is created by etching a portion of gate dielectric material toward the source end for the accomplishment of biomolecules conjugation in the proposed device. The main focus of this article is to estimate the underlying device sensitivity in the presence of different charged as well as neutral biomolecules. To explore such effects, different dielectric constants and negative charge densities of the biomolecules are considered independently in the nanogap cavity. Next, the sensing performance of the presented device is analyzed in terms of switching-ratio (I-ON/ I-OFF), transconductance-to-current ratio (g(m)/ I-ds), and average subthreshold-swing. A deep investigation of device performance is also performed with different fillings of the nanogap cavity and step-profiles arising out from the steric hindrance. The device sensitivity is analyzed for different cavity lengths and cavity thicknesses for the best outcomes. In addition, a comparative sensitivity analysis of DMGOSDG-TFET with single-material gate-oxide-stack double-gate tunnel field effect transistor (SMGOSDG-TFET) and metal-oxide-semiconductor field effect transistor (MOSFET)-based biosensor is also presented in this work. The device implementation and all the simulations are carried out using technology computeraided design (TCAD) tool. All of the sensitivity-assessments disclose that DMGOSDG-TFET can be a good candidate for biosensing applications.