InN TFET with extended gate for high sensitivity label‐free biosensor

An extended gate tunneling field effect transistor (EG‐TFET) with narrow bandgap material InN as a label‐free dielectric modulated biosensor is proposed and investigated. An optimum structure of the proposed InN TFET is given by comparing on‐state and ambipolar current. The on‐state current is improved by increasing the length of source overlap, for the rate of forward tunneling increases. Further, the ambipolar current is suppressed by increasing the length of drain offset, for the rate of backward tunneling decreases. A cavity under the gate electrode is formed for sensing biomolecules by dielectric modulation. The performance of EG‐TFET biosensor corresponding to varied dielectric constants of biomolecule is analyzed. In addition, the impacts of charge density and partial filled cavity on the drain current sensitivity are investigated. The electric field, surface potential and energy band profiles are used to explain the working principle of the EG‐TFET biosensor. The simulations reveal that the drain current sensitivity is 3.72 × 107 when neutral biomolecule with κ = 12 is immobilized in the cavity. A linearity fit verification is given, and the results of current sensitivity reveal a good linearity of the EG‐TFET biosensor with fitness coefficient γ2 > 0.99.