A Dielectrically Modulated GaN/AlN/AlGaN MOSHEMT with a Nanogap Embedded Cavity for Biosensing Applications

In this work, GaN/AlN/AlGaN MOS-HEMT with a cavity below the gate towards the drain side is studied for its sensitivity analysis and viability as a biosensor. The analysis is done by dielectric modulation of the cavity region to emulate the presence of different dielectric biomolecules and charged biomolecules by interface charge variation. MOSFET-based dielectrically modulated sensors have been a success experimentally and this work extends and demonstrates this concept with GaN HEMT. The device performance is evaluated through the shift in threshold voltage (V-th) and drain current (I-DS), which are used as performance metrics. The proposed device structure simulations were performed with ATLAS Silvaco device simulation tool which depicts the bio-immobilization in the cavity leads to the changes in electrostatic properties like conduction band offset, two-dimensional electron gas (2DEG) sheet carrier concentration and channel potential. The simulation analysis reveals V-th and I-DS shift up to 1.1 V and 153.7 mA/mm for the neutral biomolecules, whereas for deoxyribo nucleic acid, the shift is up to 0.30 mV and 65.2 mA/mm, respectively, implying a highly sensitive device. The AlGaN layer thickness and cavity fill height variations on device sensitivity are also reported.