Effect of Tunnel Junctions and Coulomb Blockade on Semiconducting Property of Networks of Single-Wall Carbon Nanotubes

Abstract

The optical and electrical characterization techniques were employed to demonstrate both experimentally and theoretically (parallel nonlinear resistor model) that the existence of tunnel junctions between semiconducting single-wall carbon nanotubes implies that the Coulomb blockade effect dominates their semiconducting property. Multiwall carbon nanotubes were added to a network of single-wall carbon nanotubes, and Raman spectroscopy and UV–vis–NIR spectroscopy enabled us to observe the semiconducting property of individual single-wall carbon nanotubes in a network with a high concentration of multiwall carbon nanotubes. However, the field effect measurement at 300 K on the network of single-wall carbon nanotubes and the electrical tunnel current measurements over a wide temperature range (4–300 K) at different bias voltages (0.001–10 V) on all of the networks revealed that the networks can be treated as networks of disordered metallic nanoparticles and the semiconducting property of single-wall carbon nanotubes is significantly diminished. Furthermore, we demonstrate that the electron tunneling in networks of carbon nanotubes cannot be fully described by models such as Efros–Shklovskii, Mott variable range hopping, electron cotunneling, or fluctuation-induced tunneling because of the diameter and length distributions in the networks. The effect of tunnel junctions on the performance of such networks for sensing applications and field effect transistors is discussed.