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

Technical Report · Thu Dec 31 04:00:00 EST 1998

DOI:https://doi.org/10.2172/554147· OSTI ID:554147

Sinclair, C K; Poelker, B M; Price, J S ^[1]

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1. Jefferson Lab., Newport News, VA (United States)

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.

• Research Organization: Southeastern Universities Research Association, Inc., Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 554147
• Report Number(s): DOE/ER/40150--1200; JLAB-ACC--96-21; ON: DE98001073
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
GALLIUM ARSENIDES
HYDROGEN
PHOTOCATHODES
SEMICONDUCTOR MATERIALS
SURFACE CLEANING