Influence of defects and temperature on the annihilation of positrons in neutron-irradiated silicon
- 1 October 1976
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 14 (7), 2709-2714
- https://doi.org/10.1103/physrevb.14.2709
Abstract
Positron-annihilation lifetime spectra have been obtained from neutron-irradiated silicon. Isochronal annealing shows that positrons trapped in divacancies have a lifetime of 325 ± 20 psec and in quadrivacancies, a lifetime of 435 ± 30 psec. From this a positron lifetime of 270 psec is predicted for monovacancies. Divacancies are found to anneal out according to a second-order process with an activation energy of 0.8 ± 0.1 eV. Breakup of divacancies is found to follow a first-order process with an activation energy of approximately 1.7 eV. The positron trapping cross section for divacancies varied with temperature approximately as , which is in good agreement with theoretical calculations based on the cascade capture model of the electron capture cross section. At 296°K the positron capture cross section was estimated to be about 4 × .
Keywords
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