STP725

    Positron Lifetime Studies of Electron-Irradiated Copper

    Published: Jan 1981


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    Abstract

    Single-crystal copper was irradiated at 80 K with 4.5 MeV electrons producing simple Frenkel defects as well as a significant concentration of multivacancies. Mean positron lifetime characteristics, which are sensitive to the presence of vacancies and multivacancies in copper, were monitored after isochronal anneals between 80 and 800 K. A study of the dependence of the mean positron lifetime on the total electron fluence was made and compared with existing theories relating these lifetimes to vacancy or multivacancy concentrations. Numerical data from curve-fitting procedures using a conventional trapping model for defect-induced changes in positron lifetimes indicate that about 8 percent of the defects produced by the irradiation were multivacancy units. Multivacancies appear to be about six times more effective in trapping positrons than are monovacancies. Further, the data suggest that Stage III annealing processes in electron-irradiated copper most probably involve the motion and removal of both monovacancies and divacancies. A conglomerate (multivacancy) unit appears to exist as a stable entity even after annealing procedures are carried out at temperatures slightly above the Stage III region. Such a stable unit could serve as a nucleation center for the appearance of voids.

    Keywords:

    positron annihilation, positron lifetime, electron irradiation, copper single-crystal irradiation, electrical resistivity, annealing, vacancies, multivacancies, void nucleation, electron fluence


    Author Information:

    Hadnagy, TD
    Senior reliability engineer, Honeywell Corp., Colorado Springs, Colo

    Byrne, JG
    Professors, University of Utah, Salt Lake City, Utah

    Miller, GR
    Professors, University of Utah, Salt Lake City, Utah


    Paper ID: STP28213S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP28213S


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