| 摘要 |
<p>PURPOSE:To improve electron emitting efficiency by forming a heterojunction with different band gaps in a base region and injecting electrons to the base region from an emitter region and at the same time applying reverse bias to the base region and a collector region. CONSTITUTION:When a reverse bias is applied between a base and an emitter with an electric power source 10, electrons in the emitter layer 2 are injected into a first base region 3. The electrons cross a heterojunction between a second base region 4 and the region 3 while running on the base. At that time, the discontinuity ALPHAEC of the bands of the heterojunction is about 0.3eV and owing to the energy level difference, the electrons injected into the base become thermal electrons. The thermal electrons are accelerated further by the electric field between the base 4 and the collector 5 and spring out to vacuum. The collector layer 5 is thinned and Cs, etc., is deposited on the surface so as to make the work function of the surface small and increase the electron emitting amount.</p> |
