Observation of Moving Dislocation Kinks and Unpinning

Atomic resolution electron microscopy has been used to obtain images of moving dislocation kinks on partial dislocations at 600 ^ in silicon. Video difference images are used to obtain direct estimates of kink velocity. Observations of kink delay at obstacles, thought to be oxygen atoms at the dislocation core, yield unpinning energies and parameters of the obstacle theory of kink motion. The kink formation energy is obtained from the distribution of kink pair separations in low-dose images and is compared to the kink migration energy. Unlike metals, kink migration rather than formation controls the velocity of unobstructed dislocations in silicon under these experimental conditions.