Thermal Conversion of Electronic and Electrical Properties of AuCl₃-Doped Single-Walled Carbon Nanotubes

By using carbon-free inorganic atomic layer involving heat treatment from 150 to 300 °C, environmentally stable and permanent modulation of the electronic and electrical properties of single-walled carbon nanotubes (SWCNTs) from p-type to ambi-polar and possibly to n-type has been demonstrated. At low heat treatment temperature, a strong p-doping effect from Au³⁺ ions to CNTs due to a large difference in reduction potential between them is dominant. However at higher temperature, the gold species are thermally reduced, and thermally induced CNT−Cl finally occurs by the decomposition reaction of AuCl₃. Thus, in the AuCl₃-doped SWCNTs treated at higher temperature, the p-type doping effect is suppressed and an n-type property from CNT−Cl is thermally induced. Thermal conversion of the majority carrier type of AuCl₃-doped SWNTs is systematically investigated by combining various optical and electrical tools.