Lawrence Berkeley National Laboratory

The objective of this project was to determine why diamond-based films are unusually efficient electron emitters (field emission cathodes) at room temperature. Efficient cathodes based on diamond are being developed by SI Diamond Technology (SIDT) as components for bright, sunlight-readable, flat panel displays. When the project started, it was known that only a small fraction (<1 percent) of the cathode area is active in electron emission and that the emission sites themselves are sub-micron in size. The critical challenge of this project was to develop new microcharacterization methods capable of examining known emission sites. The research team used a combination of cathode emission imaging (developed at SIDT), micro-Raman spectroscopy (LBNL), and electron microscopy and spectroscopy (National Center for Electron Microscopy, LBNL) to examine the properties of known emission sites. The most significant accomplishment of the project was the development at LBNL of a very high resolution scanning probe that, for the first time, measured simultaneously the topography and electrical characteristics of single emission sites. The increased understanding of the emission mechanism helped SIDT to develop a new cathode material,"nano-diamond," which they have incorporated into their Field Emission Picture Element (FEPix) product. SIDT is developing large-format flat panel displays based on these picture elements that will be brighter and more efficient than existing outdoor displays such as Jumbotrons. The energy saving that will be realized if field emission displays are introduced commercially is in line with the energy conservation mission of DOE. The unique characterization tools developed in this project (particularly the new scanning microscopy method) are being used in ongoing BES-funded basic research.