DISLOCATION IMAGING WITH A SCANNING PROTON MICROPROBE USING CHANNELING SCANNING-TRANSMISSION ION MICROSCOPY (CSTIM)

Scanning transmission ion microscopy (STIM) combined with channeling h as previously been demonstrated to be able to map regions of relativel y poor crystal quality due to beam induced damage [1,2]. This paper de scribes the implementation of the CSTIM technique on the Oxford scanni ng proton microprobe and its ability to image misfit dislocations at t he interface of an epitaxial Si0.85Ge0.15 layer grown on a (001) silic on substrate. Proton energy loss maps are generated by detecting trans mitted protons with the beam aligned with a major axis or plane of the crystal. The bending of the crystal lattice planes due to the presenc e of dislocations causes dechanneling of the beam, giving protons tran smitted through these regions a greater energy loss than those transmi tted through regions of good crystallinity. Groups of dislocations giv e rise to bands of contrast along the [110] and [110BAR] directions. C hanges in contrast on tilting the specimen are consistent with the dis locations being of the 60-degrees type rather than edge type, in agree ment with the TEM results obtained from this specimen. By imaging misf it dislocation ''cross'' patterns in a Si0.95Ge0.05 layer grown on a s ilicon substrate, it has been shown that the minimum number of disloca tions in a group that can be imaged is approximately 5 with a beam siz e of about 0.3 mum.