Investigation of dislocation mobilities in germanium in the low-temperature range by in situ straining experiments

The mobility of screw and 60° dislocations in thin, single-crystal foils of germanium has been studied by in situ tensile testing in a high-voltage electron microscope operating at 400 kV, at stresses around 40 MPa and temperatures around 400°C. The velocity of the dislocations was found to depend strongly on their length, and this is discussed in terms of a double-kink mechanism with a high lattice friction on kinks. Activation energies for kink formation and migration are deduced from fits of the velocity–length curves, and discussed in terms of core structures of partial dislocations.