Graded barrier AlGaN/GaN MOS-HEMT for ultra-sensitive and label-free detection of SARS-CoV-2

The unprecedented outbreak of COVID-19 has underscored the urgent need for advanced biosensors that are highly sensitive and cost-effective. This work investigates an AlGaN/GaN MOS-HEMT device, featuring a graded AlGaN barrier layer as a biosensor for detecting SARS-CoV-2. The proposed device integrates two nanocavity sensing regions beneath the gate to immobilize target biomolecules. Detection is achieved through dielectric and charge modulation mechanisms, targeting the neutral Spike (S) protein and the virus's charged complementary DNA (c-DNA). The performance of the device is evaluated based on shifts in threshold voltage (ΔV_th) and drain current (ΔI_DS). The simulations were carried out using the Sentaurus TCAD tool. The biosensor demonstrates significant sensitivity to the S protein, with ΔV_th and ΔI_DS reaching up to 6.9V and 437.38 mA/mm, respectively. In comparison, the c-DNA response yields a maximum ΔV_th of 2.1V and ΔI_DS of 216.75 mA/mm. Further sensitivity analysis is performed by optimizing structural parameters, therefore providing valuable insights into the design of high-performance biosensors.