Shear-activated indentation crack in GaAs single crystal

Cracks induced by 0.049N load indentation on the surface of gallium arsenide single crystal were investigated before and after annealing. The results revealed that the crack initiation essentially relates to the shear deformation during indentation. There were dislocation generation, lattice distortion, and the transformation from crystalline to disordered structure, leading to the occurrence of an amorphous band in front of the crack tip. After being annealed at 500 °C for 60 min, the amorphous band disappeared, and instead, recrystallized grains appeared along the crack-propagation direction. It is reasonable to propose that crack propagation is the result of the decohesion of the amorphous band rather than the direct debonding along a certain atomic plane.