Direct TEM determination of intrinsic and extrinsic stacking fault energies of silicon

The intrinsic and extrinsic stacking fault energies of silicon have been determined from images of double ribbons obtained using the weak–beam method of electron microscopy. The ribbons occurred in distorted regions of small–angle twist boundaries on {111} planes prepared by welding. The results are compared with values obtained from isolated dislocations in the screw and edge orientation in the same sample, which were found to be consistently lower than the values obtained from double ribbons. It is found that, contrary to other recent work, the ratio γMin γMex is actually only ∼ 14% greater than unity. © 1979 Taylor & Francis Group, LLC.