A Novel Underlay Metal Strip Loaded Doping-Less Heterojunction (GaSb/Si) TFET Biosensor for Autoimmune Disease Detection

In human being autoimmune diseases are caused by the immune system's attack on body tissues. Therefore, advanced diagnostic tools for their early and accurate detection is highly needed. This study introduces a new underlay metal strip loaded doping-less heterojunction (GaSb/Si) TFET biosensor (UMS-DL-HJ-TFETB) device with exceptional sensitivity and performance. Key design features include an underlay metal strip for improved tunnelling and the cavities are on the source region to achieve a peak drain current sensitivity of 6.7 × 10$^{10}$ at k = 12 and V$_{gs}$ = 0.45 V. With a cut-off frequency of 3.27 × 10$^{8}$ Hz and a response time of 496 ps, the proposed biosensor exhibits excellent RF performance. The device performance in detecting DNA charge densities ranging from $\pm$1 × 10$^{11}$ cm$^{-2}$ to $\pm$1 × 10$^{12}$ cm$^{-2}$ has also been studied. In addition, five non-uniform distributions which is caused by the steric hindrance effect have been optimized. A comparative analysis is also done for fair evaluation. The simulation results show that the proposed biosensor addresses the limitations of conventional methods, providing high sensitivity, rapid detection and reliable diagnostic accuracy for autoimmune diseases.