Residual stacking-fault-type contrast in silicon after apparent unfaulting reactions

Faint residual fringe contrast was observed in some regions of stacking faults (SF) in Si for which unfaulting reactions had apparently occurred. This phenomenon is attributed to an error which occurred in the apparent unfaulting process. Such an error produces, for the simplest case, a four-atom-layer-thick region on the {111} which was twinned and may also be regarded as normal {111} layers of matrix material containing an intrinsic-extrinsic SF pair. Thus, no normal SF contrast was observed; instead, the small twin boundary dilations produced the SF-like faint fringe contrast. Twin reflections were observed from such material regions.