Low Effective Work Function

In general, materials fall in three camps, conductor, semiconductor and insulator, amorphous diamond is an atomistic mixture of all, so electrons can pass through it and be emitted in vacuum. By contrast, all other materials will stop electrons either inside the crystal lattice (e.g. an insulator) or on the surface (e.g. a conductor). The unique ability for amorphous diamond to emit electrons in vacuum by receiving low levels of energy makes it the excellent of field emitter with very low apparent work function. Amorphous diamond can be coated on metallic substrate by cathodic arc process to become a useful field emitter in vacuum (Fig. 9.3).

Applied Field Strength (V/jim)

Figure 9.3. The dramatic enhancement of emission current by coating amorphous diamond on aluminum cathode with bumps.

Applied Field Strength (V/jim)

Figure 9.3. The dramatic enhancement of emission current by coating amorphous diamond on aluminum cathode with bumps.

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