Dislocation-mobility-controlled cracking in gaas caused by constantrate indentation

Abstract

The presence of a brittle to ductile transition (BDT) controlled by dislocation mobility previously found in Si has been observed for n-GaAs in the present study employing a novel type of dynamic fracture test (constant-rate indentation cracking test). This is a modification of the indentation-induced fracturing method for measuring the transition temperature, which is the critical temperature above which cracking ceases to occur as a function of loading rate. The BDT temperature thus measured was found to depend on the loading rate according to an Arrhhenius-type kinetic equation. Activation energies characterizing the equation varied with the geometrical type of crack formed by indentations on polar {111} planes of GaAs. The magnitudes of the activation energies for the BDT were found to be very close to those for motion of the dislocations that emanate from the respective types of crack tips. This result probably indicates that the BDT is caused by dislocation emission from crack tips, i.e. by a process controlled by dislocation mobility.