Atomistic Study of Crack-Tip Cleavage to Dislocation Emission Transition in Silicon Single Crystals

• Main Authors: Sen, Dipanjan (Contributor), Thaulow, Christian (Contributor), Schieffer, Stella V. (Contributor), Cohen, Alan (Contributor), Buehler, Markus J (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Civil and Environmental Engineering (Contributor), Massachusetts Institute of Technology. Department of Materials Science and Engineering (Contributor), Massachusetts Institute of Technology. Department of Mechanical Engineering (Contributor), Massachusetts Institute of Technology. Laboratory for Atomistic and Molecular Mechanics (Contributor), Buehler, Markus J. (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2011-01-21T14:35:13Z.
• Subjects: Article
• Online Access: Get fulltext

 At low temperatures silicon is a brittle material that shatters catastrophically, whereas at elevated temperatures, the behavior of silicon changes drastically over a narrow temperature range and suddenly becomes ductile. This brittle-to-ductile transition has been observed in experimental studies, yet its fundamental mechanisms remain unknown. Here we report an atomistic-level study of a fundamental event in this transition, the change from brittle cleavage fracture to dislocation emission at crack tips, using the first principles based reactive force field. By solely raising the temperature, we observe an abrupt change from brittle cracking to dislocation emission from a crack within a ≈10  K temperature interval.