Dynamic behaviour of multilayered graphene and metal-coated carbon nanotube field emitters

Field emission microscopy (FEM) and in-situ transmission microscopy (TEM) studies on electron emission from a piece of exfoliated multilayered graphene revealed that the structure of graphene edges changed from open before field emission (FE) measurement to closed after FE under high emission current over a few tens μA (10⁷-10⁸ A/cm² in current density). Dynamic behaviour of metal (Al and Au) deposited ex-situ on multiwall CNT was studied by TEM. For Al, FE hardly occurred when the film thickness was larger than ca. 1 nm. For Au, unlike Al, FE was easily occurred irrespective of thickness of Au film. During the emission, the shape of Au islands changed from flat one to special one, and after the disappearance of Au islands at the tip area, the emission current increased. Furthermore, emission fluctuation was suppressed for Au-deposited CNT emitter, suggesting the manifestation of activity of Au clusters with small sizes.