Stable room-temperature micron-scale crack growth in single-crystalline silicon

Room-temperature fracture along the (111) plane of silicon is probed at the micron-scale using chevron notched cantilever beams that enable stable crack growth before unstable fracture in successful tests. The main experimental observation is that a growing crack can extend and arrest at different stress intensity factor values within the same specimen. The present data thus provide evidence of variations in the effective Si fracture toughness along the path of a growing crack. This effect could be explained by variations in the extent of limited cracktip plasticity along the crack path. The present work also shows that the microscopic chevron notch test is, from an experimental point of view, an inconvenient method to probe the fracture toughness of silicon because it is difficult with silicon to nucleate a crack at the chevron tip at loads low enough to allow for subsequent stable crack growth.