A detailed investigation of dielectric-modulated dual-gate TMD FET based label-free biosensor via analytical modelling

In this work, an analytical model is developed for DM-DG-TMD-FET- based Biosensor including Fringing-field effects. The Analytical model has been developed for two different Device structures, namely Device structure-1 (without a gate above the nano-cavity) and Device structure-2 (with a gate above the nano-cavity) based on modulation of the dielectric constant of biomolecules in the nano-cavity region. The proposed model has been validated against both numerical quantum simulation results with the help of a few fitting parameters and it also agrees with the 2-dimensional numeric simulator SILVACO TCAD used in this work. The presence/absence of biomolecules has been detected by the metric of threshold voltage sensitivity SVth and drain current Id for the neutral as well as charged biomolecules. Sensitivities of partially filled nano-cavities arising out of steric hindrance in both the biosensors are compared. Optimization of device dimensions has also been included in this work to enhance the sensitivity of the biosensors. It has been witnessed that the sensitivity of the proposed biosensor is similar to 100% higher in Device structure-1 for neutral biomolecules with dielectric constant kappa = 12, when compared to Device structure-2 for fully filled cavities. Whereas for the charged biomolecules, Device structure-1 shows similar to 50% enhanced sensitivity than Device structure-2 for Nf=-1x10-12C/cm2. Device structure-1 demonstrates similar to 120% higher sensitivity than Device structure-2 with partially filled cavities (i.e. 66% filled cavity). Finally, benchmarking of the proposed biosensor is presented with contemporary, state-of-the-art biosensors and it is highlighted that MoS2 FET-based biosensor emerges with a superior sensitivity of SVth = 0.81 V for kappa=12.

Automated summary

An analytical model is developed for a DM-DG-TMD-FET-based Biosensor considering Fringing-field effects. The model is validated for two different device structures and agrees with numerical quantum simulation results. The sensitivity of the biosensors to the presence/absence of biomolecules is studied and compared for different device structures and partially filled cavities. The optimized device dimensions are also considered to enhance the sensitivity. The proposed biosensor is benchmarked against contemporary biosensors and shows superior sensitivity.