A Review of the Terahertz Conductivity and Photoconductivity of Carbon Nanotubes and Heteronanotubes

Terahertz (THz) spectroscopy is an ideal non‐contact and non‐destructive technique that probes the electrical conductivity of nanomaterials. This review presents the current status of research in the THz properties of quasi‐1D materials, such as nanotubes (NTs) and NT heterostructures. Detailed descriptions of THz experimental methods (THz time‐domain spectroscopy, optical pump‐THz probe spectroscopy) and conductivity extraction methods are presented along with the physical models (Drude, plasmon, effective medium theories, etc.) supporting them. Optoelectronic applications, such as optical modulators, switches, and shielding devices, are discussed and illustrate a bright future for these materials.