Study of an asymmetry tunnel FET biosensor using junctionless heterostructure and dual material gate

Abstract

In recent years, label-free sensors have been studied extensively for biomolecule detections. Label-free biosensors based on MOSFETs could achieve high detection sensitivity, the subthreshold swing of such sensors cannot break the limitation of 60 mV Dec−1 due to the physical mechanism of thermal electron emission. However, subthreshold swing less than 60 mV Dec−1 can be achieved in biosensors based on tunnel FETs working in band to band tunneling (BTBT) mode. Usually, label-free biosensors have a nanogap under the gate electrode both in MOSFET and tunnel FET (TFET), which can electrically sense the characteristics of biomolecules by dielectric constant modulation effect. In this article, we propose a novel nanogap embedded and dielectric modulated asymmetry tunnel FET biosensor with junctionless heterostructure and dual material gate, where different biomolecules can be detected effectively by adjusting the workfunctions for gate electrodes. Influences of tunnel gate, auxiliary gate and back gate workfunctions on sensitivities are explored. In addition, device-level gate effects are simulated by considering neutral and charged biomolecules. The influence of different dielectric constant at fixed charge density is also studied. Simulation results show that asymmetry dual material gate junctionless heterostructure tunnel FET (ADMG-HJLTFET) biosensor can provide higher switch ratio and higher sensitivity.