It has long been held that bulk silicon is immune from fatigue. We present contrary evidence demonstrating severe fatigue in macroscale cracks produced in cyclic loading of single-crystal silicon with a sphere indenter. The key ingredient is a component of shear stress acting on the cracks during contraction and expansion of the contact circle. This gives rise to frictional sliding at the crack walls, dislodging and ejecting slabs of material onto the silicon surface. The damage expands steadily with continued cycling, leading to degradation of the surface and, ultimately, gross surface removal. The results have implications concerning the function of silicon-based devices at both the macro- and micro-scales.
Citation: Applied Physics Letters
Pub Type: Journals
fatigue, internal friction, silicon