The electron beam-induced current contrast temperature behavior was found to constitute a so-called fingerprint which characterized the contamination level of dislocations. In the case of as-grown clean material, the dislocations exhibited only a very slight contrast, with a maximum at about 50K. At a Cu contamination of about 1ppb, the contrast increased markedly at low temperatures but remained invisible at room temperature. This behavior was attributed to the presence of shallow traps. At Cu contaminations of more than 10ppb, most of the dislocations exhibited contrast over the entire temperature range; due to the presence of near-midgap levels. The H plasma treatment of these dislocations was found to passivate the contrast near to room temperature, but did not have a marked effect upon the contrast at low temperatures. Thus, the very slight contrast which was found for clean material was not restored by H. Contamination with Cu to the ppm level resulted in a sharp increase in contrast over the entire temperature range. The use of transmission electron microscopy revealed that Cu silicide precipitates were here connected with the misfit dislocations.

M.Kittler, C.Ulhaq-Bouillet, V.Higgs: Materials Science Forum, 1995, 196-201, 383-8