Localization of He induced nanovoids in buried Si1-xGex thin films

The localization of voids in thin Si(1-x)Ge(x) layers after He(+) implantation and thermal annealing is reported. A Si/Si(1-x)Ge(x) multilayer grown onto (001) Si was implanted with He(+) in the 10-30 keV range, with fluences from 7 X 10(15) up to 1 X 10(16) cm(-2) h. Samples were analyzed by transmission electron microscopy, showing void formation only within the two layers containing Ge or at the film/substrate interface. Our results support the idea that the compressive strain in the Si(1-x)Ge(x) layers induces the nucleation of small cavities and the growth of voids by a mechanism where vacancies are stabilized by He. (c) 2008 American Institute of Physics. RI Raineri, Vito/C-5307-2009; Mirabella, Salvo/E-4672-2010