Design and analysis of Si-Ge heterostructure tunnel FET biosensors for detection of a wide range of biomolecules in both wet and dry environments

This paper reports the design and analysis of Si-Ge hetero structure planner TFET employed for the detection of various neutral biomolecules having dielectric constants ranging from 2.1 to 46.7 in both dry and wet environments. The proposed TFET sensor consists of the p ⁺Ge source attached with an n ⁺SiGe pocket extending towards the p ⁺Si channel which is attached to the n ⁺Si drain. SiO₂ acts as the receptor layer and the region of gate oxide is sculpted into a shape of rectangular cavity in which biomolecules may be included. A well-calibrated SILVACO ATLAS device simulator is employed to obtain the device transfer characteristics which are exploited to extract the sensitivity of biomolecules. The impact of molar concentration in SiGe, and also the gate source overlap length on sensitivity of biomolecules in both dry and wet environments are investigated. The variation of sensitivity is obtained with the dielectric constant of biomolecules and a comparative analysis is conducted for both dry and wet environments. The design of the sensing device is then optimised and the maximum sensitivity of 2.38 V is obtained in the wet environment condition which is higher or comparable to earlier reported data.