Performance analysis of an in-built N + pocket electrically doped TFET biosensor for biomedical applications

Abstract An in-built N + pocket electrically doped tunnel field-effect transistor (ED-TFET)-based biosensor has been reported for the first time. The proposed device begins with a PN junction structure with a control gate (CG) and two polarity gates (PG1 and PG2). Utilizing the polarity bias concept, a narrow N + pocket is formed between the source and channel without the need for additional doping steps, achieved through biasing PG1 and PG2 at −1.2 V and 1.2 V, respectively. This method not only addresses issues related to doping control but also eliminates constraints associated with thermal budgets and simplifies the fabrication process compared to traditional TFETs. To facilitate biomolecule sensing within the device, a nanogap cavity is formed in the gate dielectric by selectively etching a section of the polarity gate dielectric layer toward the source side. The investigation into the presence of neutral and charged molecules within the cavities has been conducted by examining variations in the electrical properties of the proposed biosensor. Key characteristics assessed include drain current, energy band, and electric field distribution. The performance of the biosensor is measured using various metrics such as drain current ( I DS ), subthreshold swing (SS), threshold voltage ( V TH ), drain current ratio ( I ON / I OFF ). The proposed in-built N + pocket ED-TFET-based biosensor reaches a peak sensitivity of 1.08×10 13 for a neutral biomolecule in a completely filled nanogap with a dielectric constant of 12. Additionally, the effects of cavity geometry and different fill factors (FFs) on sensitivity are studied.