A Novel Bulk Planar Junctionless Field-Effect Transistor for High-Performance Biosensing.

Biologically sensitive field-effect transistors (BioFETs) have advanced the biosensing capabilities in various fields such as healthcare, security and environmental monitoring. Here, we propose a junctionless BioFET (JL-BioFET) for the high-sensitivity and low-cost detection of biomolecules and analyze it using detailed device simulations. In contrast to the conventional FET with junctions, the JL-BioFET simplifies fabrication by doping the source, channel and drain simultaneously with the same types of impurities, thereby reducing the fabrication effort and cost. Additionally, if the device is designed with optimal bias, it can operate with only the source and drain terminals, which reduces power consumption. Thus, cost reduction and reduced power consumption are strong motivations to pursue a new design. Therefore, we simulated two JL-BioFET structures (SOI JL, bulk JL) that operate without a gate electrode and compared their biosensing performances. The bulk JL-BioFET showed an average sensitivity three times higher than that of the SOI JL-BioFET across varying charge levels. Then, we optimized the sensing performance of the bulk JL-BioFET by adjusting three key parameters: the active layer thickness and the doping concentrations of the active layer and substrate. These encouraging results are expected to lead to future fabrication efforts to realize bulk JL-BioFETs for high-performance biosensing.