Simulation and Performance Assessment of Dual-segment Recessed AlGaN/GaN HEMT Sensors for Pb2+ Ion Detection Using Functionalized SiO2-APTES

This study presents a comparative analysis of conventional single-segment (Sensor X) and recessed dual-segment (Sensor Y) AlGaN/GaN high electron mobility transistors (HEMTs) for detecting lead (Pb ²⁺ ) heavy metal ions in aqueous environments. The gate is modified with silicon dioxide (SiO ₂ ) functionalized with 3-Aminopropyltriethoxysilane (APTES) which enables effective binding of (Pb ²⁺ ) ions. The charge deduction methodology was used to evaluate the changes in the surface charge under varying lead ion concentrations. The simulation results demonstrate that Sensors X and Y achieve maximum drain current sensitivities of 17.1% and 27%, respectively. Furthermore, the effect of recess depth on Sensor Y was examined, revealing that an increase in recess depth leads to enhanced sensitivity. The effect of pH on the hydrolysis of Pb ²⁺ was also analyzed. These results confirm that the recessed dual-gate AlGaN/GaN HEMT offers enhanced sensitivity for the label-free identification of lead ions in aqueous solutions.