Design and analysis of junctionless dielectric modulated double-gate GaNFET biosensor for label-free DNA detection

The investigation of DNA hybridization spans various scientific domains, offering insights from genomics to diagnostics and pharmacology. Traditional methods involve labeling DNA, but innovative FET devices use label-free techniques. Nanoscale biosensors provide superior speed, sensitivity, cost-effectiveness, and versatility compared to conventional methods. Overcoming challenges like the Short Channel Effect (SCE) is crucial for synthesizing biosensors meeting these criteria. Previous research focused on junctionless double-gate transistors for mitigating SCE and GaN as channel materials for high-speed, low-power applications. However, dealing with negatively charged biomolecules like DNA poses challenges due to conflicting dielectric constant and interface charge effects. To address these challenges, the proposed nanoscale biosensor employs a junctionless dielectric modulated double-gate GaN field-effect transistor (JL-DM-DG GaNFET). This device effectively synergizes conflicting dielectric constant and charge effects, with GaN as the channel material. Simulation results show the n-type JL-DM-DG GaNFET exhibits significant sensitivity to negatively charged DNA, with a greater change in threshold voltage (> 539 mV for k = 1 to k = 15) compared to the p-type (-101 mV for k = 1 to k = 4, and 74.59 mV for k = 4 to k = 15). Specifically, for charge density the n-type device displays a higher sensitivity 1.05 vs. 0.509 for the p-type and for dielectric constant k = 16 (sensitivity 0.8 for n-type vs. 0.4 for p-type). Additionally, the device shows low subthreshold slope (∼ 60 mV/decay) and higher I_on/I_off ratio, suggesting faster switching and lower power consumption. In summary, the proposed n-type JL-DM-DG GaNFET holds considerable potential for efficient and reliable DNA detection.