Effect of sensitivity on the performance of dielectric–modulated asymmetrical AlGaN/GaN/InGaN/GaN MOSHEMTs for precise biosensing applications

This paper investigates a simulation based AlGaN/GaN/InGaN/GaN asymmetrical Metal Oxide Semiconductor High Electron Mobility Transistor (MOSHEMT) architecture that detects neutral biomolecules, including Zein, APTES, ChOx, Protein, Glucose, and Uricase. The device uses high-k (Al 2 O 3 ) dielectric material for simulation, offering superior electrical insulation, stable chemical properties, high surface site density (8 × 10 14 /cm²), and reduced Fermi pinning. The influence of the source-to-gate (L SG ) and gate-to-drain (L GD ) lengths on the performance of the proposed architecture is systematically evaluated in the presence of different biomolecules. Additionally, the reduction of short-channel effects, such as punch through and threshold voltage roll-off, improves scalability in advanced technologies. A 3-nm-thick In 0.1 Ga 0.9 N notch layer is incorporated into the proposed device, forming an additional potential barrier between the primary AlGaN/GaN 2DEG channel and the GaN buffer. The polarization-induced conduction-band discontinuity further results in the formation of a shallow secondary potential well at the InGaN/GaN interface, where limited carrier accumulation gives rise to a secondary conduction channel. In conjunction with the primary 2DEG, this dual-channel carrier confinement enhances electron mobility, reduces buffer leakage, and consequently improves the overall biosensing performance. The simulation analysis demonstrates an increase in drain current (I DS ) to 5.026 A/mm and a threshold voltage (V th ) of − 4.466 V for the neutral biomolecule Uricase ( k = 1.5) when L GD = 0.75 μm, compared with L GD = 0.5 μm and L GD = 0.25 μm at V GS = 2 V and V DS = 1 V. Similarly, the transconductance (g m ) and output conductance (g d ) when k = 1.5 in the cavity are 2.4 S/mm and 27mS/mm for L GD = 0.75 μm compared with the different L GD counterparts. The AlGaN/GaN/InGaN/GaN dielectric-modulated MOSHEMTs show excellent sensitivity, making them suitable for advanced biological applications.