Ge/GaAs Based Negative Capacitance Tunnel FET Biosensor: Proposal and Sensitivity Analysis

A highly sensitive, accurate, fast and power efficient biosensor is the need of the hour. Undoubtedly, dielectrically modulated (DM) tunnel FET (TFET) assures better sensitivity as compared to MOSFET biosensors in case of label-free biosensing. However, there exists immense possibilities to upgrade TFET biosensor properties through the improvement of its DC characteristics. Therefore, in this paper a ferroelectric (FE) gate oxide and a hetero material (HM) source/drain-channel based TFET is designed for biosensor applications. A FE layer of HfZrO2 above SiO2 gives rise to negative capacitance (NC) effect that causes voltage amplification and hence, boosts subthreshold swing (SS) and ION/IOFF ratio. In addition, use of a low band gap material (Ge) in source and a high band gap material (GaAs) in drain-channel junctions enhances the probability of band-to-band-tunneling (BTBT) of charge carriers. Further, to introduce biomolecules, a cavity is impinged below HfZrO2 near SiO2 above source/channel junction that modulates BTBT as a function of charge density (Nf) and dielectric constant (K). This paper presents a detailed comparative analysis of Ge/GaAs-NCTFET and Ge/GaAs-TFET biosensors for different K and Nf values from which we can conclude that the incorporation of NC effect in TFET biosensors leads to enhanced sensitivity with high speed and low power consumption.