ELECTRICAL-ACTIVITY AND MICROSTRUCTURE OF A FACETED (111)-(112), SIGMA=3 TWIN BOUNDARY IN ALUMINUM-DOPED SILICON

Electron-beam-induced current (EBIC) measurements in the scanning elec tron microscope have been correlated to analytical transmission electr on microscopy observations on a faceted SIGMA = 3 twin boundary in alu minium-doped silicon. A microfaceted region, where about 10(10) cm-2 a luminium-containing oxynitride nanoprecipitates were also present, exh ibited no EBIC contrast. On an atomic scale, the microfacets were alon g no other planes than the (111BAR) and (112BAR) twin planes, and all the observed nanoprecipitates were situated at facet intersections. Gi ven the EBIC detection limit, the concentration of electrically active bonds along these edges was estimated to be less than about 3%, which , on the one hand, corroborates the absence of deep levels predicted b y Kohyama et al. in 1990 for these defects and, on the other hand, sho ws that the electrical activity of the oxide-based precipitates is sma ll.