The discovery and understanding of the photoelectric effect led to the study of photoemissive materials fall into two major categories: classical photoemitters and negative-electron-affinity (NEA) materials. Classical photoemitters usually involve an alkali metal, a group-V element such as phosphorus, silver, and/or oxygen. An example is the Ag-O-Cs (S1) photoemitter. NEA photocathodes consist of a photoconductive single crystal semiconductor covered with a thin layer of cesium and oxygen. This layer lowers the work function of the photocathode. A dipole layer is formed at the surface, and band bending occurs. This lowers the effective work function. An example is the GaAs(CsO) photocathode (Moore, Davis, and Caplan, 1989). Other photocathodes that are noteworthy include reverse biased p-n junctions, Schottky contacts, and metal-insulator-semiconductor structures (Miller and Jones, 1980). The electrons are formed as minority carriers in a p-type semiconductor and are then emitted over the metallic surface barrier that has been treated with cesium to lower its work function.

Original Publication Citation

W.I. Karain, Larry V. Knight, David D. Allred and A. Reyes-Mena, "Manufacturing of atomically sharp silicon tips and their use as photocathodes," Encyclia: The Journal of the Utah Academy of Sciences, Arts and Letters. 69, 257-272 (1992). [http://www.utahacademy.org/].

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Peer-Reviewed Article

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Utah Academy of Sciences, Arts, and Letters




Physical and Mathematical Sciences


Physics and Astronomy