Thermal dissipation and variability in electrical breakdown of carbon nanotube devices

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 simulations. Experiments and modeling find the CNT-substrate thermal coupling scales proportionally with CNT diameter and inversely with SiO2 surface roughness (similar to d/Delta). Comparison of diffuse mismatch modeling and data reveals the upper limit of thermal coupling similar to 0.4 W K-1 m(-1) per unit CNT length at room temperature, (130 MW K-1 m(-2) per unit area), and similar to 0.7 W K-1 m(-1) at 600 degrees C for the largest diameter (similar to 3.2 nm) CNTs. We also find semiconducting CNTs can break down prematurely and display more 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.