Patent ID: 8143615

Claim:
An electron beam emitting device having a superlattice structure, comprising: a plurality of well layers made of a first semiconductor; and a plurality of barrier layers made of a second semiconductor that has an electron affinity smaller than that of the first semiconductor, wherein the well layers and the barrier layers deposited alternately, and wherein: each thickness of the well layers and each thickness of the barrier layers are determined such that a band gap between a lower limit of a first mini band generated in a conduction band and an upper limit of a second mini band generated in a valence band is a given width in an energy state of electrons in the superlattice structure and a bandwidth of the first mini band generated in the conduction band is a given width in the energy state of electrons in the superlattice structure, an energy level in a vacuum is lower than the lower limit of the first mini band generated in the conduction band, and when the superlattice structure is irradiated with a light having such a wavelength that excites electrons from the second mini band generated in the valence band to the first mini band generated in the conduction band, an electron beam having a monochromatized energy state is emitted to the vacuum.