Carbon-based composite nanomaterials as cold cathode sources

Here we develop a novel type of bulk nanomaterial for effective cold cathode applications. We call in question an importance of the diamond for effective carbon emitters and produce a set of nanocomposite samples in which different insulating particles were used such as nanopowders of silicon oxide, boron nitride in cubic and hexagonal forms, as well as nanodiamond. The samples of non-diamond/pyrocarbon and diamond/pyrocarbon composite nanomaterials were prepared by the same technique, in which the matrix is pressed from nanoparticles and then saturated with pyrocarbon during a CVD process. Each kind of the samples was made at a set of different growth conditions to study an influence of the sample structure on the field emission and to find an optimal structure for efficient emission and cold cathode applications. The structure of the composites was studied using micro-Raman spectroscopy and SEM. Special STM study of emission intensity, work function, electrical conductivity, and topography maps of the emission centers was made to understand the nature of the emission in the materials. An original mechanism of the emission is supposed basing on quantum properties of nanostructured carbon forms including reduction of the tunneling barrier on insulator/graphite interfaces due to quantum well effects for thin (two-dimensional) carbon nanolayers covering the dielectric particles.