Abstract
This paper demonstrated the plasma post-treatment (ppt) process for modifying the granular structure of ultrananocrystalline diamond (UNCD) films so as to improve their electron field emission (EFE) properties. The ppt-processed UNCD films exhibited improved EFE properties as turn-on field of E 0 = 7.0 V/μm (J e = 0.8 mA/cm 2 at 17.8 V/μm). TEM investigation revealed that the prime factor, which enhanced the EFE properties of the UCND films, is the induction of nano-graphitic clusters due to the ppt-process. However, for achieving such a goal, the granular structure of the primary UNCD layer has to be relatively open. That is, the size of grains should be sufficiently small and the grain boundaries should be of considerable thickness, containing abundant hydro-carbon species. Such a simple and robust process for synthesizing conductive UNCD films is especially useful for practical applications.