Field emitter density control effect on emission current density by Ag–Cu alloy coating on carbon nanotubes

Abstract

We have investigated the morphological evolution and improvement in field emission properties of carbon nanotube (CNT) emitters coated with an Ag–Cu alloy (ACa). Vertically aligned multiwalled CNTs (MWCNTs) were synthesized by direct current-plasma enhanced chemical vapor deposition. The MWCNTs were then coated with ACa by dc-magnetron sputtering and then annealed. Scanning electron microscopy revealed an increase in the size of the ACa droplets on the CNTs after thermal annealing, and a decrease in the emitter density with increasing deposition time. The emitter density was controlled by the amount of ACa with high surface tension and annealing. A lower turn-on voltage (1.18 V/μm) and higher emission current density of 588.9 μA/cm2 at 5.0 V/μm were achieved from the sample containing ACa droplets with an average radius of 500 nm.