Field emission properties of metallic element-containing glassy carbon films

Field emission properties of metallic element-containing glassy carbon (GC) films were investigated. The metallic element-containing GC films were prepared by carbonization process (i.e., heat treatment in an inert atmosphere) of synthesized polyimide including a metallic compound. In the alkaline (lithium(Li) or cesium(Cs)) or alkali-earth (calcium(Ca), strontium(Sr), or barium(Ba)) metallic element-containing GC films, threshold electric field, Eth, decreased and emission current density, J, increased. In particular, as for the Ba-containing GC film, Eth was decreased to 1.5 V/μm compared with Eth of 3.5 V/μm for the pure GC film without the metallic element addition, and the J reached more than 0.8 mA/cm2 at an electric field of 3.0 V/μm. Analysis based on the Fowler-Nordheim model suggests that the amplification of the local-field-conversion factor β and/or the lowering of the effective-surface-potential barrier ϕ are due to the metallic elements contained in the GC films. Moreover, structural and compositional analyses showed that compositional modification of the GC film by the metallic elements plays an important role in allowing easy field emission.