Enhanced field emission from metal-coated carbon nanowalls

Fine-grained metals with sizes as small as 10 nm are deposited on nitrogen-incorporated carbon nanowalls to enhance field emission. The amount of metal coating is varied using the nominal thickness to control morphology and coverage of metal nanoparticles. The emission turn-on field decreases down to around 1.6 V um^-1 and 1.8 V um^-1 with increasing thickness of Ag and Au to 2 nm and 4 nm, respectively, and increases for further increase in thickness. A lower turn-on field corresponds well to a larger field enhancement factor, confirming that additional field enhancement with the morphological evolution of metal nanoparticles governs emission performance.