Claims
- 1. A photocathode for emitting a photoelectron in response to light in an infrared region incident thereon, said photocathode comprising:
a substrate comprising InP of a first conduction type; a buffer layer, formed on said substrate, comprising InAsx2P1−x2(0<x2<1) of the first conduction type lattice-matching said substrate; a light-absorbing layer, formed on said buffer layer, comprising Inx1Ga1−x1As (1>x1>0.53) of the first conduction type lattice-matching said buffer layer; an electron-emitting layer, formed on said light-absorbing layer, comprising InAsx3P1−x3 (0<x3<1) of the first conduction type lattice-matching said light-absorbing layer; a contact layer, formed on said electron-emitting layer with a predetermined pattern so as to expose said electron-emitting layer with a substantially uniform distribution, comprising InAsx3P1−x3 of a second conduction type; an active layer, formed on the exposed surface of said electron-emitting layer, comprising an alkali metal or an oxide or fluoride thereof; a first electrode formed on said contact layer; and a second electrode formed in said substrate.
- 2. A photocathode according to claim 1, wherein the As composition ratio x2 of said buffer layer changes stepwise or continuously from said substrate side to said light-absorbing layer side.
- 3. A photocathode according to claim 1, wherein said buffer layer comprises a superlattice layer formed by stacking a plurality of thin films having As composition ratios x2 different from each other.
- 4. An electron tube constituted by encapsulating the photocathode according to any of claim 1 and an anode into a vacuum envelope.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Provisional Application Ser. No. 60/220,654 filed on Jul. 25, 2000, which is hereby incorporated by reference in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
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60220654 |
Jul 2000 |
US |