Resistivity reduction of boron-doped multi-walled carbon nanotubes   synthesized from a methanol solution containing a boric acid
  Boron-doped multi-walled carbon nanotubes (MWNTs) were synthesized using a methanol solution of boric acid as a source material. Accurate measurements of the electrical resistivity of an individual boron-doped MWNT was performed with a four-point contact, which was fabricated using an electron beam lithography technique. The doped boron provides conduction carriers, which reduces the resistivity of the MWNT. 
Satoshi Ishii, Tohru Watanabe, Shinya Ueda, Shunsuke Tsuda, Takahide   Yamaguchi, and Yoshihiko Takano