Field Emission of Gallium-Doped Carbon Nanotubes

Abstract

Field emission property of Ga-doped carbon nanotube (CNT) film has been studied and compared with those of un-doped, N-doped as well as B and N co-doped CNT films. It is found that the Ga-doped CNT film exhibits superior field emission property to the other films. The turn-on field for Ga-doped CNT film is well below 1.0 V/μm, lower than those for un-doped (2.22 V/μm), N-doped (1.1 V/μm), B and N co-doped (4.4 V/μm) CNT films. Its current density reaches 5000 μA/cm2at 2.6 V/μm which is well above those for un-doped (1400 μA/cm2), N-doped (3000 μA/cm2) as well as B and N co-doped (2) CNT films at applied electric field of 5.7 V/μm. First principles calculations were carried out to obtain the binding energy and electronic nature altering of a CNT by Ga doping. It is shown that Ga-doped CNT (8,0) alters from semiconductor to intrinsic metal and a binding energy of 2.7527 eV is obtained. The field emission property can not simply be explained by the defect concentration, but can be understood by significant altering in the local density of states near the Fermi level introduced by dopants.