The Au nanoparticles attached carbon nanotubes (Au-CNTs), diameter ranged from 40 to 250 nm, were prepared and discussed their chemical and electrical properties. The shape and crystallinity of the carbon nanotubes (CNTs) phase depended mainly on the diameter of CNTs (r(Au-CNT)). Highly crystalline, straight CNTs were observed when the r(Au-CNT) exceeded 80 nm, and less crystalline noodle-shaped CNTs were observed when the r(Au-CNT) was smaller than 80 nm. The crystallinity of the CNT phase was confirmed by analyzing the G and D bands in their Raman spectra and the electrical conductivities of the Au-CNTs. The electrical conductivity of the highly crystalline carbon phase of Au-CNTs (r(Au-CNT) = 250 nm) was similar to 10(4) S/cm. The back-gated field effect transistors (FETs) based on the Au-CNTs, which were assembled on a SiO2/Si wafer using the dielectrophoresis technique, showed that the Au-CNTs would be a good functional electronic material for future electronic and sensing applications. The transconductance and hole mobility of the FETs, which were assembled with the highly crystalline Au-CNTs (r(Au-CNT) = 250 nm), reached to 3.6 x 10(-4) A/V and 3.1 x 10(4) cm(2)/V s, respectively. These values are in the middle of those of reported for single walled carbon nanotubes and graphene. However, we could not find any field effect in a CNTFET, which assembled without Au nanoparticles, through the same process. (C) 2016 Elsevier B.V. All rights reserved.