The occurrence of As-enhanced diffusion along individual misfit dislocations in Si/SiGe heterostructures was detected and imaged by using scanning electron microscopic and electron beam induced current methods. The formation of buried cylindrical, or conical, diodes surrounding misfit dislocations was observed. The diffusion enhancement was not uniform for each dislocation. The EBIC/SEM micrographs revealed a dark recombination contrast in the vicinity of the dislocation core, and a white generation signal within the space-charge region of the surrounding n/p diode. On the basis of experimentally determined iso-concentration etching profiles, and a simple model for enhanced diffusion, the dislocation diffusion coefficient for As was estimated to be up to 6 orders of magnitude higher than that in the host crystal.

N.Braga, A.Buczkowski, H.R.Kirk, G.A.Rozgonyi: Applied Physics Letters, 1994, 64[11], 1410-2