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US 4,053,920 AGranted
Step graded photocathode
AssigneeThe United States of America as represented by the Secretary of the Army
InventorRonald E. Enstrom
Life of this patent
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Abstract
A method is provided for making an improved photocathode wherein a step ged substrate links a semitransparent cathode made from one p-type III-V compound or complex to a different III-V compound in the form of a host crystal.
Claims2
A III-V photocathode comprising
- host crystal of substantially pure III.sup.A V material;
- a series of graded layers of transition material approximately 2 microns thick and having a stochiometric formula III.sub.X.sup.A III.sub.1-x.sup.B V.sup.M deposited on said host crystals, where the value of x is varied in steps to provide an abrupt increase of 8-10 mole percent of III.sup.A -V in each successive graded layer as compared with the underlying material, the last of said graded layers containing between 30 - 58 mole percent of III.sup.A V;
- final layer of said transition material containing 40 - 65 percent of III.sup.A V approximately 5 microns thick deposited over the last of said graded layers;
- and
- a photocathode layer composed of III-V compounds at least one of which is different from those in said transition material deposited on said final layer and activated with cesium vapor and oxygen.
2 more elements
Dependencies are inferred from the claim text.