A sustainable junctionless FET biosensor with dual nanocavities for high-sensitivity medical diagnostics

The demand for high-sensitivity, label-free biosensors has driven the evolution of advanced field-effect transistor (FET) designs. In this work, a novel biosensor architecture, hybrid junctionless FET with nanocavity in the channel and gate region (HJLFET-CG), is presented, which integrates nanocavities in both the silicon channel and the gate dielectric. This hybrid configuration synergistically combines the strengths of dielectric modulation and direct channel interaction to enhance sensitivity and scalability. The proposed device, designed using 45 nm technology and simulated via the Silvaco ATLAS TCAD platform, demonstrates superior performance compared to traditional designs that utilize nanocavities in only one region. Simulation results show that the HJLFET-CG exhibits significantly improved current sensitivity, reduced subthreshold swing, and lower threshold voltage across a range of biomolecular dielectric constants and charge states. Furthermore, design optimization studies identify 15 nm as the ideal nanocavity length and 4 nm as the optimal gate oxide thickness for peak sensitivity. The device also maintains strong linearity and selectivity, making it suitable for accurate differentiation of biomolecules under various sensing conditions. These results establish the HJLFET-CG as a promising platform for next-generation, low-power, high-sensitivity biosensing applications.