Design and Simulation of Source-engineered TFETs for Low-power Applications

Abstract

The thesis addresses the imperative need for low-power electronic devices, which is crucial intoday's technology landscape where energy efficiency and portability are paramount. TraditionalMOSFETs, while prevalent, face significant challenges when scaled down for low powerapplications, particularly due to high leakage currents and suboptimal performance at lowervoltages. Tunnel Field-Effect Transistors (TFETs) emerge as a viable solution due to their abilityto achieve steeper subthreshold slopes (SS), enabling lower operational voltages and reducedpower consumption. However, TFETs inherently suffer from limitations such as low ON-current(ION) and ambipolarity, which hinder their widespread adoption. To mitigate these issues, thisresearch explores advanced source engineering techniques to enhance TFET performance. Thestudy begins with the double gate TFETs (DGTFET), followed by an investigation into broken gateTFETs (BG-TFET), focusing on optimizing parameters such as drain doping concentration, gate-drain underlap, and drain split configurations. A significant advancement is achieved byintroducing a Germanium source in the broken gate TFET (Ge-BG-TFET), aimed at improvingthe ION. Subsequently, a novel N+ Pocket broken gate TFET (N+ Pocket BG-TFET) is proposedto address the limitations observed in the Ge-BG-TFET. The culmination of this research is thedevelopment of a novel Germanium-Source N+ Pocket broken gate TFET (Ge-S N+ Pocket BG-TFET) structure. This innovative design, combining the advantages of both Germanium sourceand N+ Pocket engineering, exhibits remarkable performance metrics. Simulations conductedusing SILVACO ATLAS TCAD software demonstrate an ION of 1.82??10-4A/??m, IOFF of 4.33??10-18A/??m, an ION/IOFF ratio of 4.21??1013, a SS of 29.19 mV/decade, and a Vth of 0.37534 V. Theseresults indicate a substantial improvement in device efficiency, effectively overcoming the low IONchallenge of traditional TFETs while maintaining low power operation.Furthermore, the applicability of the proposed TFET structure is validated through its applicationin biosensing, showcasing its potential in scenarios. This comprehensive approach underscoresthe importance of source engineering, particularly material and shape engineering, in developinghigh-performance, low-power TFETs. The thesis provides a robust framework for the design andsimulation of next-generation TFETs, contributing significantly to the advancement of low-powerelectronics