Screening of positrons in semiconductors and insulators

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1989
Major/Subject
Mcode
Degree programme
Language
en
Pages
7666-7679
Series
Physical Review B, Volume 39, Issue 11
Abstract
Theoretical models are presented for the enhancement of the electron density at a positron in a semiconductor or insulator host. The model better suited for typical semiconductors is based on the many-body theory for the screening of a positron in electron gas. The starting point of the model for insulators is the atomic polarizability. The common parameter in both models is the high-frequency dielectric constant. Moreover, the enhancement depends on the ambient electron density in the semiconductor model and on the unit-cell volume in the insulator model. With use of the models developed, positron lifetimes in perfect semiconductor and insulator crystals have been calculated. In the calculations, three-dimensional electron densities and electrostatic potentials are obtained by atomic superposition and the fully three-dimensional positron wave functions are solved by a relaxation method. The calculated positron lifetimes agree with the experimental ones within a few picoseconds. Moreover, we have used the model to predict lifetimes of positrons trapped by lattice defects such as vacancies and vacancy clusters.
Description
Keywords
semiconductors, positrons, electron density
Other note
Citation
Puska, M. J. & Mäkinen, S. & Manninen, M. & Nieminen, Risto M. 1989. Screening of positrons in semiconductors and insulators. Physical Review B. Volume 39, Issue 11. 7666-7679. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.39.7666.