Strategic Interventions to Suppress Ambipolar Conduction in Schottky Barrier CNTFETs for Digital Circuits

Abstract

Carbon Nanotubes (CNTs) Field Effect Transistors (CNTFETs) offer solutions to the newlinescaling challenges of current IC technology. CNTFETs can be scaled aggressively with minimal short channel effects. Room temperature ballistic transport of charge carriers and the demonstrated potential to yield high performance at low operating voltages makes them an attractive alternate for MOSFETs. Despite all these striking characteristics, CNTFETs are yet to make their debut in the main stream IC fabrication technology. The reasons behind this are: 1. Presence of misaligned and metallic CNTs, 2. Variations in CNT diameter and chirality, 3. Ambipolar conduction in CNTFETs causing high leakage currents. Ambipolar behavior is characterized by the superposition of hole current and electron current. This work takes up the third issue and aims at suppressing the ambipolar conduction in CNTFETs. The metal-contacted configuration is perfect for nanoscale devices since metals have significantly lower parasitic resistance when compared to heavily doped semiconductors. Therefore, a Schottky Barrier CNTFET (SB CNTFET) is chosen. SB CNTFET works on the principle of direct tunnelling through the Schottky barrier at the source-channel junction. The objective of the present doctoral research work is to intervene and explore various strategies to suppress ambipolar conduction in SB CNTFETs and present them as a viable alternative to the existing silicon technology newline