Terahertz detection mechanism and contact capacitance of individual metallic single-walled carbon nanotubes

TL;DR

This study investigates how metallic single-walled carbon nanotubes detect terahertz radiation, revealing that contact nonlinearity primarily drives the response and that contact capacitance is smaller than previously thought, benefiting high-frequency applications.

Contribution

It provides a detailed model of the contact capacitance and detection mechanism in metallic carbon nanotubes, offering new insights into their high-frequency device potential.

Findings

Contact capacitance is smaller than previous estimates.

Terahertz response is mainly due to contact nonlinearity.

Small contact capacitance favors high-frequency applications.

Abstract

We characterize the terahertz detection mechanism in antenna-coupled metallic single-walled carbon nanotubes. At low temperature, 4.2 K, a peak in the low-frequency differential resistance is observed at zero bias current due to non-Ohmic contacts. This electrical contact nonlinearity gives rise to the measured terahertz response. By modeling each nanotube contact as a nonlinear resistor in parallel with a capacitor, we determine an upper bound for the value of the contact capacitance that is smaller than previous experimental estimates. The small magnitude of this contact capacitance has favorable implications for the use of carbon nanotubes in high-frequency device applications.