Comparative investigation of extended-gate GaAsSb/InGaAs HTFET biosensors for label-free biomolecule detection.

The dielectric-modulated heterostructure tunnel FET (HTFET)-based nano-cavity integrated biosensors are emerging as energy-efficient, ultra-sensitive label-free detection platforms. This study investigates and compares three GaAsSb/InGaAs-based biosensor architectures: single cavity dual material double composite gate HTFET (SC-DM-DG HTFET), dual cavity dual material double composite gate HTFET (DC-DM-DG HTFET), and single cavity dual material extended double composite gate HTFET (SC-DM-EDG HTFET). The III-V heterostructure in the SC-DM-EDG HTFET enhances tunnelling probability, gate control, and on-current (ION), thereby providing higher sensitivity than previously reported GaAsSb/InGaAs-based HTFET and FET biosensors. Sensitivity and selectivity parameters for ION, transconductance (gm), and threshold voltage (Vth) were evaluated for various neutral and charged biomolecules. Under the standard bias condition (VDS = 1.5 V, VGS = 1.3 V), the SC-DM-EDG HTFET exhibits the highest ION of 3.02 × 10-4 A/μm among the three structures; under a separately re-optimized bias (VDS = 0.9 V, VGS = 1 V), the same structure instead achieves maximum sensitivities of 3.35 × 106 (ION) and 3.49 × 105 (gm) for K = 12, at a correspondingly reduced ION of 1.91 × 10-4 A/μm. The maximum Vth sensitivity of 0.49 is achieved by this structure under the standard bias condition. In biomolecule differentiation, the SC-DM-DG HTFET demonstrates peak ION and gm selectivity values of 9.55 and 4.64 for K = 12, respectively, while the peak Vth selectivity value of 0.3 appears in the SC-DM-EDG HTFET also for the same biomolecule. Furthermore, the SC-DM-EDG HTFET achieves superior ION, gm, and Vth sensitivities for charged biomolecules, confirming its robustness, selectivity, and potential for next-generation, high-performance biosensing applications.