High-sensitivity biosensor based on junctionless transistor using Si/Si 0.5Ge0.5 hybrid heterostructure: A potential device for SARS-CoV-2 sensing

In this paper, the performance of silicon-on-insulator junctionless (JL) transistors is reported as a biosensor for SARS-CoV-2 (COVID-19) detecting through proteins of virus using the dielectric modulated method (DMM). In this structure, which is designed based on Si/Si0.5Ge0.5 hybrid heterostructures junctionless transistor (HH-JLT), both cavities are placed on the side of the gates. In this way, the optimization of device is performed for cavity design by considering the effect of Hf02 regions as a spacer. The performance of the biosensor for detection is proven by analyzing the important parameters such as threshold voltage, ION/IOFF ratio and transconductance (gm). For the optimal proposed structure, the threshold voltage (Vth) and subthreshold slope (SS) sensitivity are obtained 7.5 and 0.45 respectively, for biomolecules with K=4.1. In addition of the DC sensitivity analysis, the sensitivity of RF parameters such as cutoff frequency (ft), transconductance generation factor (TGF), transconductance frequency product (TFP) and gain bandwidth product (GBW) is evaluated for charged biomolecules, the results exhibit that the increase in sensitivity with charge density changes is also considerable.