Terahertz electrical conductivity and optical characterization of composite nonaligned single- and multiwalled carbon nanotubes

Abstract

We employed noncontact terahertz time-domain spectroscopy to investigate and compare the electrical/optical properties of nonaligned single-walled carbon nanotube and nonaligned multiwalled carbon nanotube thin films. Using Drude–Lorentz model together with the Maxwell Garnett effective medium theory, we determined the electrical conductivities from the extracted data of differential complex terahertz analysis in the frequency range of 0.1 to 2 THz. The results demonstrate that the conductivity of isotropic single-walled carbon nanotube thin film is almost two times larger compared to isotropic multiwalled carbon nanotube thin film due to the increased number of surface defects and the availability of mobile carriers. By using Drude–Lorentz model, the broadening optical density and conductivity can be studied at higher frequencies.