Electron-emitting device, electron source using the electron-emitting devices, and image-forming apparatus using the electron source

An electron-emitting device comprising:

• first and second electrodes arranged on a surface of a substrate;
• first and second carbon films;
• and
• a voltage source, for applying a voltage between said first electrode and said second electrode, to emit electrons,
• wherein a first end of said first carbon film is electrically connected to said first electrode, a first end of said second carbon film is electrically connected to said second electrode, a second end of said first carbon film and a second end of said second carbon film are disposed in opposition to each other across a gap, the second end of said first carbon film being more distant from the surface of the substrate than the second end of said second carbon film, and said voltage source applies a potential greater than a potential of the second electrode to said first electrode in order to emit electrons,
• wherein the surface of the substrate is concaved at a section within the gap.