Single-walled carbon nanotubes as a dopant in p-type cuprous oxide films

p-type cuprous oxide (Cu2O) films doped with single-walled carbon nanotubes (SWCNTs) were synthesized using the two-step process of electrochemical co-deposition and subsequent thermal oxidation. SWCNTs are known to act as a conducting pathway in various SWCNT-based composite materials because of their low electrical resistivity in the longitudinal direction. However, they act as an electron acceptor dopant rather than a carrier pathway in p-type Cu2O. Results show that the doping of SWCNTs in Cu2O films increases the hole concentration and decreases the carrier mobility with increasing dopant concentration. As a result, the electrical resistivity decreased from 290 to 0.8 Ω cm as the amount of dopant increased. The electronic energy band structure, as determined by X-ray and ultraviolet photoelectron spectroscopy, revealed that the doping of SWCNTs moved the Fermi levels of Cu2O films toward the valence band maximum by 0.24 eV. This confirms that the SWCNTs act as an electron acceptor and increase the hole concentration and electrical conductivity of the Cu2O films, despite the lower mobility.