This book presents a groundbreaking Dual Metal Double Gate Tunnel Field Effect Transistor (DM DG TFET) featuring a laterally divided dielectric gate oxide structure with a tunneling and auxiliary gate. By engineering gate oxides and work functions, the device achieves a sub-threshold swing below 90 mV/decade, high current ratio, and ultra-low OFF current. It explores the role of high-k dielectrics, doping, and gate potentials in optimizing performance. The research further introduces a charge plasma-based TFET for label-free biomolecule detection, demonstrating exceptional drain sensitivity and RF response. A Heterojunction Ferroelectric Charge Plasma TFET design enhances switching speed and biosensing accuracy. Bridging innovation with simulation, this work establishes TFETs as key components for next-generation electronics and biosensing technologies.