Open gate AlGaN/GaN HEMT biosensor: Sensitivity analysis and optimization

Abstract

In this work, a physics based analytical model has been proposed for an open gate AlGaN/GaN HEMT for electrical detection of biomolecules-uricase, glucose, biotin and cytochrome -c. The proposed device is easy to fabricate and offers high sensitivity at low operating voltages as complete gate area has been used for immobilizing biomolecules. The analytical model has been developed for evaluating drain current sensitivity and threshold voltage sensitivity by considering that the gate electrode is immersed in solution of de-ionized (DI) water. Results obtained by analytical model are in good agreement with previously reported experimental data and have also been verified with simulation results. Detailed sensitivity analysis has been carried out by evaluating additional electrical parameters such as gate-source capacitance, channel potential, channel conductance and transconductance to detect the presence of biomolecules. Barrier thickness, channel width to length ratio (W/Lsd) and Al composition in barrier layer have been optimized to obtain high sensitivity. The maximum drain current and threshold voltage sensitivity obtained for uricase is 3.95 × 108 and 820 mV respectively.