Dielectric Modulated Enhancement Mode N-Polar GaN MIS-HEMT Biosensor for Label Free Detection

In this paper, an n-polar GaN MIS-HEMT based biosensor is proposed for label-free detection of various bio-molecules such as uricase, streptavidin, protein, and ChOx. Numerous reports exist on the experimental demonstration of underlap MOSFET-based biosensors but the concept has never been previously utilized in n-polar GaN MIS-HEMT based sensors. This work focuses on the characterization and sensitivity analysis of n-polar GaN HEMT based biosensor using Silvaco TCAD. For the bio-species immobilization, an open cavity is formed underneath the gate by etching away the gate and the gate insulator material from the middle of the channel region to form an underlap area. The immobilization of analytes in the underlap region leads to variation in electrostatic properties of device such as drain current, channel potential, and threshold voltage which can be used as sensing metrics. It is observed that there is a significant increase in drain current and output conductance with the addition of different biomolecules in the nanocavity. A maximum shift in threshold voltage is observed when uricase is put in the nanocavity due to its low dielectric constant. The effect of the position of biomolecules inside the cavity on sensitivity is also studied.