Field emission properties of carbon nanotubes deposited by electrophoresis

Field emission properties of carbon nanotubes (CNTs) deposited by electrophoresis were investigated. Uniform deposition of CNTs on 1 x 1 cm(2) of Ti substrate was observed by scanning electron microscopy (SEM). In addition, in case of CNTs synthesized by arc discharge, purification of CNTs was also obtained due to the higher electrophoretic velocity of carbon nanotubes than those of other carbon species. It indicates that electrophoresis can be used as the purification method of CNTs. As the result of I-V measurement, CNTs synthesized by arc discharge showed the lowest turn-on-field (J = 30 nA/cm(2)) of 1.77V/mum. On the other hand, CNTs synthesized by vapor phase growth showed a little higher turn-on-field of 2.28 V/mum. Moreover, turn-on-field of acid treated CNTs had the highest value of 2.77 V/mum. These differences might result from the difference in the electrical conductivity as well as the structural quality of CNTs such as wall and caps structures, radius, defect density, and density of CNTs. (C) 2002 Elsevier Science B.V. All rights reserved.