| 摘要 |
PROBLEM TO BE SOLVED: To enable electron emission efficiency to be improved by providing a porous semiconductor layer formed on a semiconductor layer of an electron emission element for emitting electrons by applying an electric field between the semiconductor layer and a metal thin film electrode with at least two porous layers having their different porosity each other in its film thickness direction. SOLUTION: This electron emission element comprises a semiconductor layer 12 for supplying electrons of an Si substrate, for example, provided with an ohmic electrode, a Si-porous semiconductor layer 13 made porous by anode- oxidizing this Si-semiconductor layer 12, and a metal thin-film electrode 15 facing a vacuum space. The porous semiconductor layer 13 comprises at least two or more porous layers having their different porosity each other, and a porous layer 13a with its high porosity in its film thickness direction and a porous layer 13b with its low porosity are alternately laminated. The entire porous semiconductor layer 13 has its film thickness of 1 to 50 micrometers. |
