Uniformity conditioning of diamond field emitter arrays
SEM micrographs of a DFEA; wide view (left) and tip detail (right).
Schematic of the close-diode conditioning arrangement. Anode-cathode gap is typically , and the applied potential of .
Detail of beams from individual DFEA tips. Each beam comprises multiple beamlets from adsorbed species that fluctuate due to adsorbate diffusion and adsorption/desorption. The tips are laid out on a square grid with a pitch.
Uniformity improvement for a array following a VTEC treatment. The active emitter fraction increased from (left) to (right). Intensity values have been inverted for clarity.
Uniformity improvement for a array following a VTEC treatment. Left (before); right (after).
Typical emission current behavior during a VTEC treatment. The temperature equilibrated to a maximum value of after .
Emission uniformity progression during HCC of a DFEA. Images were taken at progressively higher fields, ending at . The uppermost tip was malformed during fabrication and not expected to emit.
DFEA nanotips before (top) and after (bottom) HCC up to per tip. Tips are noticeably shorter with increased tip radii.
DFEA emission images before (left) and after (right) HCC. The histogram was generated by binning the integrated intensity of each beamlet.
HCC progression for a ungated DFEA. No significant emission uniformity changes are noted until an average per-tip current of .
Typical morphology evolution of a DFEA emitter during the HCC process.
Roughly uniform distribution of backsputtered anode material on the cathode surface following moderate current operation.
Self-correction of fabrication and postprocessing defects during HCC. The top and bottom are separate tips, and the conditioning progression moves left to right.
Tips from a pitch ungated DFEA before (four tips on left) and after (four tips on right) HCC and back bombardment damage. The before and after pictures are not of the same emitters but are representative of the array.
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