| 摘要 |
<p>PURPOSE:To increase quantity of electrons emitted by injecting electrons from a 1st range to a 2nd range and emitting the electrons from an electron emission surface in the 2nd range. CONSTITUTION:In forming a heterojunction structure of a 1st layer 8 including a 1st band gap, and a 2nd layer 10 including a 2nd band gap which is narrower than the 1st band gap on an epitaxial film of GaAs provided on a substrate 1 of Si, an inclined layer 20 in which ratio of mixed crystals of a certain material is gradually changed is inserted between the 1st layer and the 2nd layer, and electrons are injected from the 1st layer to the 2nd layer, while the electrons are emitted from an electron emission surface of the 2nd layer. Due to insertion of the inclined layer 20 between the layer 8 and the layer 10, ratio x of mixed crystals of A1 is gradually reduced, reaching 0 at the boundary with the base layer 10. Because of this insertion of the inclined layer 20, spikes or the like are not produced in the hetero-boundary between the layer 8 and the layer 10. Thus quantity of electrons emitted can be extremely increased.</p> |
