Dislocation loops in silicon-germanium alloys: The source of interstitials

摘要

The relationships between extended defect evolution and boron diffusion in Si_(0.77)Ge_(0.23) have been investigated. A SiGe structure was grown by molecular beam epitaxy with a 3 x 10~(18) atoms/cm~3 boron marker layer positioned 0.50 μm below the surface. Samples were ion implanted with 60 keV Si~+ at a dose of 1 x 10~(14) atoms/cm~2 and subsequently annealed at 750℃ for various times. The evolution of extended defects in the near surface region was monitored with plan-view transmission electron microscopy. Secondary ion mass spectroscopy concentration profiles facilitated the characterization of boron diffusion. Boron experiences transient enhanced diffusion regulated by the dissolution of dislocation loops. The maximum diffusion enhancement in Si_(0.77)Ge_(0.23) is less than that observed in pure Si.