ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
The influence of Cu contamination on radiation-induced defect reactions in n-typeCzochralski-grown silicon (Cz-Si) crystals has been studied by means of the Hall effect technique,deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS with supportingtheoretical modeling of defects.It is found that the contamination of Cz-Si samples with Cu does not influence significantly theenergy spectrum and introduction rates of the principal electrically active defects induced byelectron irradiation. The vacancy-oxygen (VO) centre, divacancy (V2) and a complex consisting ofa silicon self-interstitial with the oxygen dimer (IO2) are found to be the dominant radiation-induceddefects in Cu-contaminated samples as well as in uncontaminated ones. An isochronal annealingstudy has shown that the presence of Cu affects the annealing behaviour of the vacancy-relateddefects. In Cu-doped samples the VO centre disappears upon annealing at significantly lowertemperatures (175-250°C) compared to those of the VO disappearance in the uncontaminatedsamples (300-375°C). The disappearance of the VO centres in the Cu-doped samples occurssimultaneously with an anti-correlated introduction of a defect with an energy level at about Ec-0.60 eV. It is suggested that this defect is formed by the interaction of a mobile Cu atom with theVO complex. According to results of quantum-chemical modelling, in the most stableconfiguration of the Cu-VO defect a Cu atom occupies a tetrahedral interstitial position nearest tothe elongated Si-Si bond of the VO centre. The presence of the Cu atom is found to result in thefurther elongation of the Si-Si bond and a shift of the VO acceptor level to the middle of the gap.The annealing behaviour of V2 has also been found to be different in the irradiated Cu-dopedsamples compared to that in the uncontaminated ones. The most probable reason for this differenceis an interaction of mobile Cu atoms with di-vacancies. An energy level at about Ec-0.17 eV hasbeen tentatively assigned to a complex consisting of a Cu atom and a di-vacancy
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.131-133.363.pdf
