Motion of dislocations from an indentation rosette on silicon crystals

The average velocities of leading dislocations in arrays emitted from a hardness impression on silicon crystals are measured as the dislocations of the indentation rosette (IR) are subjected to a bending stress (6 to 60 MN m−2) for a known period of time at different test temperatures (773 to 1073 K). Specimens are not etched after the generation of the dislocations before the application of the bending stress. Experimental results obtained are compared with results obtained previously on specimens from the same silicon ingot but on isolated dislocations or on those generated from a scratch without polishing away some of the dislocations before bending. It is found that stress and temperature dependence of the leading dislocation velocity satisfy the same power-law equation but the values of the stress exponent (m) are higher with the exception when the test temperature is around 870 K and that the activation energy is only slightly different. In the lower stress region (τ < 10 MN m−2) and at a temperature of around 970 K, the average velocity of the leading dislocations is found to be lower than that of the isolated dislocations.