Application of scanning tunneling-field emission microscopy for investigations of field electron emission from nanoscale diamond films

A special scanning tunneling-field emission microscope (STFEM) has been use d for studying field electron emission from thin nanocrystalline diamond fi lms grown by a DC plasma CVD. These are characterized by turn-on electric f ields as low as 3.5 V/mu m and by long-term stability of the emission curre nt. Comparing different surface properties (topography, field electron emis sion intensity, surface potential and local electroconductivity distributio ns) on a large surface area it was found that, in most cases, emission cent re position is not coincident with peaks of the surface profile. It has bee n noted that the diamond films studied are composed from nano-grained phase s distinguished by their physical properties. These are thought to be diamo nd and graphitic phases. The low-field electron emission from the samples s tudied is considered to be associated with the presence of these phases. Th e results of the STFEM mapping have been compared with data on macroscopic current/field field emission characterization. The mechanisms governing low -held electron emission from nanoscale diamond films are discussed. (C) 199 9 Elsevier Science B.V. All rights reserved.