Design and Optimization of Heterojunction-Based FET Device for Low-Power Bio-sensing Application

Abstract

Addressing the limitations of traditional biosensors, this work presents a high-sensitivity, low leakage HTFET architecture using advanced material and structural innovations. A source engineered TFET is analyzed by comparing conventional TFETs with Indium Phosphide (InP) drain TFETs, significantly reducing ambipolar leakage. A comparative analysis of Indium Antimonide (InSb) and Germanium (Ge) as source materials on InP and Si drains confirms superior InP drain performance. A Ge-source extended structure with a highly doped Si pocket at the source-channel interface improves ON-state current (I_ON). Further enhancements include a dielectric pocket at the channel-drain junction to suppress ambipolar current and an InSb source pocket for higher drive capability. Electrical characterization of vertical TFETs with SiGe pockets supports their suitability for biosensing applications.Two dielectric modulated FET biosensors are designed: (1) InAs/InGaAs HTFET and (2) Ge split-source HTFET, both simulated using Silvaco Atlas TCAD. The heterojunction interfaces and narrow bandgap materials enhance tunneling sensitivity. The InAs/InGaAs HTFET achieves I_ON of 4.355 × 10⁻⁵ A/μm, I_OFF of 5.117 × 10⁻¹⁴ A/μm, and an I_ON/I_OFF ratio of 8.51 × 10⁹, with a subthreshold swing (SS) of 18.2 mV/dec, ensuring energy-efficient biosensing. Sensitivity evaluations for streptavidin, ferricytochrome, keratin, and gelatin demonstrate superior drain current sensitivity compared to the Ge Split-Source HTFET. This work addresses conventional FET biosensor limitations, advancing high-sensitivity, low-power sensing for healthcare diagnostics, environmental monitoring, and industrial automation. The findings emphasize material selection, heterojunction engineering, and structural optimization for biosensor performance improvement.