Diamond/W Microcathode/Microcathode Array with Very High Field Emission Current Density

Diamond has recently emerged as a promising material for electron field emission due to its unsurpassed properties of low voltage and room temperature operation, operation robustness, simple design, and reproducibility. However, the present diamond cathodes, which are microcrystalline diamond thin films deposited on macro-substrate (mm to cm size ) suffer a few drawbacks. Only 1-10% or less of the diamond cathode surface is active and contributes nearly all the current produced, resulting in an overall low emission efficiency. The distribution of the minority populated active emission sites is also random and uncontrolled. The electron emission from each individual emission site cannot be independently controlled either. This Phase I program proposes to develop a novel diamond/W microcathode and microcathode array by synthesizing and depositing nanocrystalline diamond thin films on the ends of micron diameter W fibers through a unique diamond chemical vapor deposition (CVD) process. The novel diamond/W microcathode/microcathode array is expected to exhibit significantly improved emission efficiency and current density at low operation field, controlled emission performance and emission pattern. The Phase II program will optimize the fabrication process and produce prototype diamond/W microcathodes/microcathode arrays. Because of the high efficiency, the cost of the new diamond cathodes will be substantially reduced. The availability of diamond microcathodes will also be beneficial to microtechnology of electronics and optoelectronics, and will significantly reduce the size of the conventional diamond cold cathodes.