Observations of dislocation motion in solar-grade polycrystalline material were performed  in situ  in a high-voltage electron microscope. When compared with previous measurements of monocrystalline Si, the dislocation velocities were found to be increased. This was attributed to a recombination enhancement that was due to the excess carriers which were created by the electron beam. A detailed analysis revealed that the migration barrier was reduced by about 0.6eV. This value was consistent with earlier measurements which proved that the dislocation mobility was enhanced by near-bandgap illumination. However, whereas the so-called photo-plastic effect was observed only at temperatures below 450C, the cathodo-plastic effect was evident here at temperatures of up to 690C. It was proposed that recombination enhancement of the dislocation motion was caused by recombination-assisted kink formation rather than by recombination-enhanced kink migration.

M.Werner, E.R.Weber, M.Bartsch, U.Messerschmidt: Physica Status Solidi A, 1995, 150[1], 337-41