Anisotropic Fracture Energy of Boron-Doped P-Type Silicon by Microindentation: Influence of Temperature and Crystallographic Orientation

This study investigates the anisotropic fracture behavior of boron-doped p-type single-crystal silicon on the (001) plane, under varying temperatures and crystallographic orientations, utilizing Vickers’ indentation experiments. Measurements performed at 25 °C, 50 °C, and 90 °C, reveal a strong dependence of mechanical properties—such as hardness, fracture toughness (K_1c), and fracture energy—on both temperature and crystallographic orientation. At room temperature, the fracture energy peaks at 7.52 J/m² along the [100] direction, with a minimum of 4.42 J/m² along the [110] direction. As the temperature rises to 90 °C, the fracture energy decreases across all orientations, where values drop to 5.13 J/m² and 3.65 J/m² for the [100] and [110] directions, respectively. In contrast to pure, undoped silicon, the unexpected reduction in fracture energy with increasing temperature is likely due to dislocations pinned by the substitutional boron dopant at elevated temperatures, as well as the weakening of atomic bonds from thermal expansion. This valuable insight is critical for designing silicon-based devices, where understanding the fracture properties at elevated operating temperatures is important for ensuring reliability and performance.