Gate-Dependent Electron Transport in Semiconductor-Enriched Single-Walled Carbon Nanotube Networks
Although individual metallic single-walled carbon nanotubes (SWNTs) have lower resistance than individual semiconducting SWNTs, a metallic-enriched SWNT network can have a higher resistivity than a semiconductor-enriched SWNT network. This is because semiconductor-enriched SWNT networks could have different Fermi energies from the intrinsic SWNT network by unintentional doping. To control the Fermi energy, we are developing a field-effect transistor using a SWNT film as a channel. We will also use an annealed sample, which should have fewer dopants and thus be more intrinsic. By measuring the resistivity of the channel as a function of gate voltage at various temperatures, we can figure out how much the SWNT film is doped because the gate voltage cause a shift of the Fermi energy, and thus the carrier density, of SWNTs.