| 摘要 |
<p>PURPOSE:To provide a photoelectron emitting surface having remarkably higher sensitivity in comparison with a conventional photoelectron emitting surface using a semiconductor and able to extend a critical wave length to a far longer wavelength, and an electron tube using this surface. CONSTITUTION:Since a GaAs layer 22a of a heterojunction semiconductor multi- layer film to be a light absorbing layer 22 has a film thickness of 300Angstrom or less which is shorter than the de Brogie wave length of an electron, it forms a potential well being interposed by adjacent Al0.65Ga0.35As layers 22b each having a large energy gap, and a sub band in accordance with a quantum level is formed in the GaAs layer 22a. Since the Al0.65Ga0.35As layer 22b has a film thickness equal to or thicker than 45Angstrom which an electron can not pass through due to a tunnel effect, this sub band is all the time filled with bound electrons.</p> |
