Transport properties of multi‐walled carbon nanotubes grown by boron addition method

Abstract

The transport property of boron‐doped multi‐walled carbon nanotubes (MWNTs) was investigated. The boron‐doped MWNTs were grown by a novel CVD process using a methanol solution of boric acid as a source material. In order to evaluate the transport property accurately, the electrical conductivity of each individual MWNT was measured by a four‐point method. Nano‐sized four electrodes with a width of several hundred nanometers were fabricated on an individual MWNT using electron beam (EB) lithography. The conductivity of a boron‐doped MWNT was one or two orders of magnitude higher than that of a non‐doped MWNT at room temperature. Furthermore, the boron‐doped MWNT was found to maintain a high conductivity at a very low temperature of 0.6 K, while the non‐doped MWNT became an insulator. The electrical conductivity of the MWNTs was increased by boron doping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrical properties of boron-doped MWNTs synthesized by hot-filament chemical vapor deposition

“…An Si substrate covered with thermally grown SiO 2 (500 nm thick) was placed within 1 mm below the filament. Before the growth, the surface of the substrate was coated with an Al layer (5 nm thick) by thermal evaporation, and then coated with an iron acetate by dipping followed by heating at 400 o C for 5 min [3][4][5]9]. When the voltage was applied to the filament, the source solution in the left flask was boiled by the heated filament.…”

“…To evaluate the electrical properties, the temperature dependence of resistivity was measured from room temperature down to 2 K. For accurate measurement, a four-terminal method was performed with metal electrodes, which were fabricated on an individual target MWNT by electron beam lithography [3].…”

“…An Si substrate covered with thermally grown SiO 2 (500 nm thick) was placed within 1 mm below the filament. Before the growth, the surface of the substrate was coated with an Al layer (5 nm thick) by thermal evaporation, and then coated with an iron acetate by dipping followed by heating at 400°C for 5 min [3][4][5]9]. When the voltage was applied to the filament, the source solution in the To evaluate the electrical properties, the temperature dependence of resistivity was measured from room temperature down to 2 K. For accurate measurement, a four-terminal method was performed with metal electrodes, which were fabricated on an individual target MWNT by electron beam lithography [3].…”

“…Many approaches to control the resistivity using chirarity were attempted because the electrical properties of CNTs strongly depend on the chirarity [1,2]. In our previous work, we have synthesized boron-doped multiwalled carbon nanotubes (MWNTs) by thermal chemical vapor deposition (CVD) using a methanol solution of boric acid as a source material [3][4][5]. The electrical resistivity of the boron-doepd MWNTs was successfully reduced by increasing the boron concentration up to 2.0 atm% in the source solution.…”

A Simple Method for Preparation of Highly Conductive Nitrogen/Phosphorus-Doped Carbon Nanofiber Films

“…Aromatic heterocycles can be introduced to increase the content of heteroatoms after carbonization at the same time [ 8 ]. In another material modification, introducing mesophase pitch [ 23 ], carbon nanotubes [ 24 ], PAN [ 25 ], and boric acid [ 26 , 27 ] into ECNF precursors for blending modification is also an effective method to improve the conductivity and increase the doping content of ECNFs. Among them, PAN and polyamic acid (PAA) have good compatibility [ 25 , 28 ] and improve the spinnability of PAA [ 25 ].…”