| 摘要 |
<p>PROBLEM TO BE SOLVED: To efficiently supply electrons to a diamond layer for emitting electron beams from the diamond surface by providing a hole-blocking semiconductor layer consisting of an electron injection electrode and a n-type semiconductor, which are brought into contact with each other, and an electron injection semiconductor layer consisting of a semiconductor with a band gap narrower than that of the n-type semiconductor. SOLUTION: At impressing of an electric field, a conduction band 18 in each layer is connected smoothly from an electron supplying electrode 11 to an electron discharging surface 15 in a diamond layer 14, so that the electrons are efficiently supplied along this direction. On the other hand, there is present a valence band 19 possessing a barrier wall 1G between an electron supplying semiconductor layer 13 and a hole blocking semiconductor 12, so that holes advancing from the diamond layer 14 towards the electron supplying electrode 11 are trapped by means of the barrier wall 1G, and their conduction is inhibited. Consequently, electrons can be supplied efficiently without inhibition because of conduction of holes, so that the electrons can be discharged efficiently.</p> |
