Effect of temperature on fracture toughness in a single-crystal-silicon film and transition in its fracture mode

A change in the fracture mode of a micrometer-sized single-crystal-silicon (SCS) film was observed at a temperature slightly higher than room temperature (RT). Silicon films with a notch on one side were tested under tensile stress at temperatures ranging from RT to 500 °C. The mean fracture toughness was 1.28 MPa at RT and the value remained similar up to 60 °C. However, it drastically increased to nearly twice this value above 70 °C. Differences in the fracture mode and dislocation activity were found by scanning and transmission electron microscopy (SEM and TEM). These results show that the fracture mode changed even at a low temperature near 70 °C due to the activation of dislocations at the notch tip.