High temperature induced brittle-ductile transition of monocrystalline silicon via in-situ indentation

Monocrystalline silicon is difficult to molding process due to the unknown mechanism of temperature-influenced brittle-plastic transition. Indentation test of monocrystalline silicon from room temperature (RT) to 500 ℃ was carried out within scanning electron microscope (SEM). Evolution of surface damage mode at elevated temperatures were in-situ observed. Cracking and extrusion occurred during indentation of monocrystalline silicon from RT to 200 ℃, while shallow scallop-shell lateral peeling was found to be generated by a combination of secondary radial crack and shallow lateral crack. The phenomenon of surface peeling disappeared at 300 ℃. The plasticity of the material significantly increased. Dislocation motion coexists but competes with microcrack nucleation-expansion with temperature increasing. The completion of the brittle-plastic transition is evident at 500 °C. Cracks are no longer generated on the surface and pile-up phenomenon is enhanced. This discovery demonstrates the feasibility of plastic molding processing of monocrystalline silicon at high temperatures.