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

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 / μ m ) and higher emission current density of 588.9 μ A / cm 2 at 5.0 V / μ m were achieved from the sample containing ACa droplets with an average radius of 500 nm.