2011
ACL
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M.Canino, G.Regula, M.Xu, E.Ntsoenzok, M.F.Barthe, T.Sauvage, E.Oliviero, B.Pichauda, 'Roles of local He concentration and Si sample orientation on cavity growth in amorphous silicon', Philos. Mag. 91 4324-4331 (2011) doi:10.1080/14786435.2011.617715
(111)- and (100)-oriented Si samples were implanted with Si(+) ions at 1 MeV to a dose of 1 X 10(16) cm(-2) and with 5 X 10(16) He(+) cm(-2) at 10 keV or 50 keV and eventually annealed in the 800-1000 degrees C temperature range. Sample characterisation was carried out by cross-section transmission electron microscopy, positron annihilation spectroscopy and nuclear reaction analysis. In addition to the formation of He bubbles at the projected range of He, bubbles were observed after solid-phase epitaxial growth (SPEG) of the embedded amorphous Si layer. The He threshold concentration required to obtain thermally stable bubbles in amorphised Si is between one and four orders of magnitude lower than in c-Si. Since bubble formation and growth take place in the a-Si phase, the interaction with SPEG during annealing was studied by considering (100) and (111) Si. Both the SPEG velocity and the resulting defects play a role on bubble spatial distribution and size, resulting in bigger bubbles in (111) Si with respect to (100) Si.
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