We present the results of the study of the sensitivity of a dielectrically-modulated GaSb/Si dual-material stacked double-gate hetero-junction tunnel field effect transistor (GaSb/Si DMSDG-HJTFET) as a biosensor capable of detecting the onset of diseases. We consider asymmetrically-doped source, channel, and drain regions with gate work function engineering and a gate stack structure involving \(HfO_2\) on \(SiO_2\) along with III–V/Si hetero junction. A nanocavity has been created by selectively removing a portion of the gate dielectric material close to the source end to achieve the biomolecule conjugation in the biosensor. To assess the inherent sensitivity of the device when exposed to charged as well as neutral biomolecules, we examine independently both charged as well as neutral biomolecules within the nanogap cavity, considering several values for the dielectric constant (k) and charge density ( \(\rho\) ). The analysis of electrical performance of the biosensor has been carried out concerning the energy band diagram, tunneling rate, surface potential, electric field, transconductance, transfer characteristics, and output characteristics. The efficiency of the biosensor for the label-free detection is quantified by its sensitivity on peak drain current, transconductance, and \({\text{I}}_{\text{on}}/{\text{I}}_{\text{off}}\) ratio. Further, in order to analyse the reliability of the biosensor, different real-time scenarios of partially filled cavities with different fill factors have been considered. Moreover, several step profiles have been taken into account, which emerge due to steric hindrance. The design and simulation of the biosensor has been carried out using the Silvaco TCAD tool. The simulation results demonstrate that GaSb/Si DMSDG-HJTFET biosensors can be a potential alternative for biosensing applications.
