Direct observation of damage accumulation process inside silicon under mechanical fatigue loading

Fatigue test was performed on single crystal silicon under humid environment in an environmental scanning electron microscope. While the specimen was repeatedly subjected to compressive stress, electron beam induced current (EBIC) images were obtained to visualize damage evolution. Local contrast changes were successfully observed at the notch tip, which remained the same through the hydrofluoric acid treatment after the experiment. These facts suggest that damage evolved inside silicon crystal during the fatigue loading process and that the contrast change was not due to an oxide layer thickened on the surface.