Evaluation of Design and Performance of Biosensor Utilizing Ferroelectric Vertical Tunnel Field-Effect Transistor (V-TFET)

In this work, a novel Ferroelectric gate oxide along with high-k dielectric HfO2 is introduced in the Vertical TFET structure to incorporate the negative capacitance effect. The effects of ferroelectric gate oxide in addition with SiGe heterojunction pocket at source-channel junction improve the performance of the device for biosensor application. A negative capacitance (NC) effect is produced by adding the FE layer over HfO2 by EOT (equivalent oxide thickness), which enhances overall capacitance with reduced SS and OFF current. An n + doped of SiGe material pocket at source channel junction will improve the BTBT of the charge carriers due to low band gap SiGe material. For the Biosensing application of this device, a cavity is added above the source channel junction and below the FE layer, in parallel to HfO2. The integration of bio-molecules their charge density (qf), and their dielectric constant (k), collectively modulates the effective dielectric constant of the gate oxide and hence causes a change in the surface potential and drain current though which the sensitivity of the bio-molecules is determined. The impact of the temperature and cavity length variation is also analyzed on the sensitivity determination. A comparative analysis of ferroelectric VTFET vs non ferroelectric vertical TFET and TFET has been done for bio-sensing application with reference to characteristics like drain current, electric field and surface potential. The highest ON current value recorded for FE-VTFET as 1.02169 x 10-4 (A/mu m) whereas normal VTFET has 7.56141 x 10-5 for the bio-molecules having relative dielectric constant is k = 12. The results shows that the negative capacitance improves sensitivity of labeled and label free biosensors significantly.