Threshold auto-emission management for nanocrystalline diamond graphite structures

Theoretical and experimental research of nanostructured carbon materials with adjustable transparency of the tunnel barriers that control the threshold of their autoemission are presented. It is shown that increasing the transparency of the potential barrier at autoemission can be accomplished by increasing self-energy of the tunneling electron at size quantization. The role of surface states in nanodiamond emitting centers in the mechanism of electron transport from the conductive graphite matrix is considered. The conditions for obtaining nanostructured carbon structures with adjustable phase ratio for nanodiamand and carbon were determined. At this conditions autoemission threshold voltage can be change from 20-40 V/μm to 5-7 V/μm. Reducing autoemission threshold allows to increase the current densities at lower intensities of the external electric field, increase the life time and autoemission stability of the used cathode materials.