Gate All Around Junctionless Dielectric Modulated BioFET Based Hybrid Biosensor Design, Simulation and Performance Investigation

Here in this work, we demonstrate the concept of hybrid biosensor based on embedded cavity gate all around (GAA) junctionless field effect transistors (JLT) capable of sensing, amplification and noise cancellation simultaneously for the first time. The disadvantages of low sensitivity and noise in classical concept of single device biosensor system are mitigated using a hybrid scheme, where sensing is performed by p-type and n-type FETs simultaneously. The proposed hybrid biosensor is designed by exploiting dielectric modulation property of embedded nanogap cavity biologically sensitive field effect transistors (DM-FETs). Lookup table (LUT) based Verilog-A models are developed for p and n type devices considering various types of biosamples in the embedded nanogap cavity. The developed Verilog-A models are imbibed into Cadence Virtuoso to perform the circuit simulations. The biomolecules are simulated as dielectric materials with different permitivities in the embedded nanogap cavity. The proposed hybrid biosensor has been analyzed for different topologies and performance comparisons have been carried out between junctionless based DM-FET and inversion mode DM-FET based biosensors. The performance of proposed DM-FET based hybrid biosensor has been evaluated through voltage transfer characteristics (VTCs) in terms of logic threshold voltage shift (Delta V-Lt) and gain (A(V)). Performance comparisons for different topologies including resistive load, single stage and cascaded two stage hybrid biosensors have also been analyzed. Cascaded GAA JLT configured biosensors yields the highest Delta V-Lt sensitivity of 61.14%. However the results emphasize the superior all-round performance of cascaded CMOS configuration with Delta V-Lt similar or equal to 30% and gain A(V)= 55.