Momentum distributions of electron-positron pairs annihilating at vacancy clusters in Si

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1998
Major/Subject
Mcode
Degree programme
Language
en
Pages
7621-7627
Series
Physical Review B, Volume 57, Issue 13
Abstract
We report calculations of momentum densities of electron-positron pairs annihilating at various vacancy clusters in Si. The densities integrated along one direction, i.e., those corresponding to the spectra measured by the two-dimensional angular correlation of the annihilation radiation method, are shown to be isotropic if the positron is captured by a small vacancy cluster. The densities integrated along two directions correspond to the one-dimensional angular-correlation distribution or the Doppler-broadened annihilation radiation line shape. The characteristic narrowing of these one-dimensional distributions at vacancy clusters is demonstrated. The line-shape parameters S and W describing mainly the annihilations with valence and core electrons, respectively, are calculated and compared quantitatively with experimental data. We find a systematic increase in the S and a decrease in the W parameter as the size of the vacancy increases.
Description
Keywords
Si, electron-positron pairs
Other note
Citation
Hakala, M. & Puska, M. J. & Nieminen, Risto M. 1998. Momentum distributions of electron-positron pairs annihilating at vacancy clusters in Si. Physical Review B. Volume 57, Issue 13. 7621-7627. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.57.7621.