Thermal Dissipation and Variability in Electrical Breakdown of Carbon Nanotube Devices

TL;DR

This study investigates the thermal dissipation, breakdown behavior, and variability in carbon nanotube devices on SiO2, combining experiments, modeling, and simulations to understand heat transfer and failure mechanisms.

Contribution

It provides new insights into the thermal coupling between CNTs and substrates, and highlights the impact of CNT type and substrate roughness on electrical breakdown variability.

Findings

Thermal coupling scales with CNT diameter and inversely with substrate roughness.

Upper limit of thermal coupling is approximately 0.4 W/K/m at room temperature.

Semiconducting CNTs exhibit more breakdown variability due to threshold voltage shifts.

Abstract

We study high-field electrical breakdown and heat dissipation from carbon nanotube (CNT) devices on SiO2 substrates. The thermal "footprint" of a CNT caused by van der Waals interactions with the substrate is revealed through molecular dynamics (MD) simulations. Experiments and modeling find the CNT-substrate thermal coupling scales proportionally to CNT diameter and inversely with SiO2 surface roughness (~d/{\Delta}). Comparison of diffuse mismatch modeling (DMM) and data reveals the upper limit of thermal coupling ~0.4 W/K/m per unit length at room temperature, and ~0.7 W/K/m at 600 C for the largest diameter (3-4 nm) CNTs. We also find semiconducting CNTs can break down prematurely, and display more breakdown variability due to dynamic shifts in threshold voltage, which metallic CNTs are immune to; this poses a fundamental challenge for selective electrical breakdowns in CNT electronics.