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Electric field-induced point electron source is highly demanded for microscopy, spectroscopy, lithography, X-ray tubes, microwave devices, and data displays. However, the instability in emission current and requirement of ultrahigh vacuum have often limited its extensive applications. Herewith we report a single-crystalline HfC nanowire with oxycarbide emission surface for stable electron emission at 50 nA with fluctuations less than 1% in a vacuum of 4 × 10-7 Pa. The emitter has a low work function of 2.5 eV measured by the field emission Fowler-Nordheim curve and it is in good agreement with density functional theory (DFT) calculations. The energy spread is in a range of 0.21-0.26 eV with a corresponding reduced brightness 1.95 × 1011-3.81 × 1011 A·m-2·sr-1·V-1. The HfC nanowire with oxycarbide emission surface is a qualified candidate for the next-generation electron source with high brightness, large current, and low energy spread.
We thank Prof. K. Hono for helpful discussions on the FIM and atom probe results. This work was supported partially by the NIMS-DENKA Centre of Excellence for Next Generation Materials. A part of this work was also supported by NIMS Microstructural Characterization Platform as a program of "Nanotechnology Platform" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.