Exposure of GaAs to atomic hydrogen for cleaning prior to NEA photocathode activation

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Description

Creating an atomically clean semiconductor surface is an essential step in preparing negative electron affinity (NEA) photoemission cathodes. While bulk GaAs can be satisfactorily cleaned by chemical etching and in situ heat cleaning, many high polarization electron source materials are either much too thin, or have oxides and carbides which are too tightly bound, to be cleaned by these methods. Some polarized source candidate materials may be degraded during the heat cleaning step. It is well established that the exposure of many III-V, II-VI, and elemental semiconductors to atomic hydrogen, typically at elevated temperatures, produces semiconductor surfaces free of contamination. ... continued below

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4 p.

Creation Information

Sinclair, C.K.; Poelker, B.M. & Price, J.S. December 31, 1998.

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This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 21 times , with 4 in the last month . More information about this report can be viewed below.

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Description

Creating an atomically clean semiconductor surface is an essential step in preparing negative electron affinity (NEA) photoemission cathodes. While bulk GaAs can be satisfactorily cleaned by chemical etching and in situ heat cleaning, many high polarization electron source materials are either much too thin, or have oxides and carbides which are too tightly bound, to be cleaned by these methods. Some polarized source candidate materials may be degraded during the heat cleaning step. It is well established that the exposure of many III-V, II-VI, and elemental semiconductors to atomic hydrogen, typically at elevated temperatures, produces semiconductor surfaces free of contamination. Furthermore, this cleaning, possibly followed by thermal annealing, leaves surfaces which show sharp LEED patterns, indicating good stoichiometry and surface order. Atomic hydrogen cleaning should eliminate the chemical etching step, and might reduce the temperature and/or temperature-time product presently used in forming NEA cathodes. The process is readily adaptable to in situ use in ultrahigh vaccum.

Physical Description

4 p.

Notes

OSTI as DE98001073

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  • Other Information: PBD: [1998]

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  • Other: DE98001073
  • Report No.: DOE/ER/40150--1200
  • Report No.: JLAB-ACC--96-21
  • Grant Number: AC05-84ER40150
  • DOI: 10.2172/554147 | External Link
  • Office of Scientific & Technical Information Report Number: 554147
  • Archival Resource Key: ark:/67531/metadc694207

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  • December 31, 1998

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  • Aug. 14, 2015, 8:43 a.m.

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  • Feb. 17, 2017, 6:17 p.m.

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Sinclair, C.K.; Poelker, B.M. & Price, J.S. Exposure of GaAs to atomic hydrogen for cleaning prior to NEA photocathode activation, report, December 31, 1998; Newport News, Virginia. (digital.library.unt.edu/ark:/67531/metadc694207/: accessed August 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.