https://doi.org/10.1051/epjap:2007018
Grown-in vacancy-type defects in poly- and single crystalline silicon investigated by positron annihilation
1
Department of Physics, University of Winnipeg, 515 Portage Avenue,
Winnipeg, Manitoba, Canada R3B 2E9
2
Topsil Semiconductor Materials, Linderupvej 4, PO Box 100, 3600
Frederikssund, Denmark
Corresponding author: sdannefaer@shaw.ca
Received:
7
February
2006
Revised:
16
September
2006
Accepted:
20
November
2006
Published online:
24
January
2007
Positron annihilation was used to characterize vacancy-type defects in two types of polycrystalline Si grown at temperatures above ~800 °C by chemical vapour deposition. The majority of vacancies (80%) consisted of monovacancies, and their thermal stability indicated them to be trapped at grain boundaries or at dislocations. Annealing above 500 °C caused a significant reduction in the monovacancy concentration, and an increase in divacancy concentration. Divacancies started to anneal above 1200 °C. Measurements between 8 and 293 K indicated that vacancies were neutral before as well as after annealing at 1380 °C. Fz-grown Si from one of these materials contained vacancy clusters with an average size of six to ten vacancies which persisted to 1380 °C. The cluster concentration corresponded to a monovacancy concentration of 1015 to 1016 cm−3, which is at least one order of magnitude larger than estimates based on voids [R. Falster, V.V. Voronko, F. Quast, Phys. Status Solidi B 222, 219 (2000)].
PACS: 61.82. Fk – Semiconductors / 61.72.Ji – Point defects (vacancies, interstitials, color centers, etc.) and defect clusters / 78.70.Bj – Positron annihilation (for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
© EDP Sciences, 2007
