Shear stress enhanced fatigue damage accumulation in single crystalline silicon under cyclic mechanical loading

In contrast to the commonly accepted hypothesis where surface oxide layer is supposed to play a dominant role on fatigue fracture of silicon, another scenario newly appeared here being supported by a series of evidences which showed crystal slip deformation leading to fatigue damage accumulation. Two different types of specimens with different shear/tensile stress ratios on {111} crystal slip plane were designed and subjected to fatigue loading. Lifetime was eventually longer with smaller shear stress working on this plane. Striation-like fracture surface patterns were also observed, which should have been created before unstable fracture took place. Even dislocation networks were discovered at the fracture initiation site. Silicon may behave in a much more metallic manner even at room temperature than was ever believed before, no wonder finally leading to fracture under cyclic mechanical loading.