Design Optimization of AlGaN/GaN HEMT Biosensors for Enhanced Biomolecule Sensitivity: Gate Dielectric and Spacing Effects

This study examines the impact of gate dielectric materials and gate-to-drain spacing (LGD) on the performance of AlGaN/GaN HEMT biosensors for uric acid (UA) biomolecule detection using TCAD simulations. The commonly used gate dielectrics materials such as SiO2, HfO2, Al2O3, and Si3N4 have been analyzed under UA concentrations of 55 to 460 µM. The SiO2 exhibited highest drain current shift (ΔIDS = 8 mA/mm) and sensitivity (145.5 µA/µM), while Al2O3 achieved the largest threshold voltage shift (ΔVTH = 1.72 V) and sensitivity (31.3 V/mM). Changes in LGD showed a peak in both ΔVTH and ΔIDS at an optimal spacing, after which sensitivity decline can be attributed to the increased series resistance and weak electrostatic control. These findings highlight the importance of material selection and device geometry in enhancing GaN-based biosensor sensitivity.