Drain Voltage Scaling in Carbon Nanotube Transistors

TL;DR

This paper investigates how reducing oxide thickness in CNFETs necessitates scaling the drain voltage to prevent exponential increases in Off-current caused by Schottky barrier modulation, providing a practical scaling rule.

Contribution

It introduces a specific drain voltage scaling rule for CNFETs with thin oxides to control Off-current and improve device performance.

Findings

Scaling drain voltage is essential for thin-oxide CNFETs.

Exponential Off-current increase occurs without voltage scaling.

Light emission is observed at high Off-current conditions.

Abstract

While decreasing the oxide thickness in carbon nanotube field-effect transistors (CNFETs) improves the turn-on behavior, we demonstrate that this also requires scaling the range of the drain voltage. This scaling is needed to avoid an exponential increase in Off-current with drain voltage, due to modulation of the Schottky barriers at both the source and drain contact. We illustrate this with results for bottom-gated ambipolar CNFETs with oxides of 2 and 5 nm, and give an explicit scaling rule for the drain voltage. Above the drain voltage limit, the Off-current becomes large and has equal electron and hole contributions. This allows the recently reported light emission from appropriately biased CNFETs.