Amorphization and nanocrystallization of silicon under shock compression

• Autores: Zhao, S.; Hahn, E. N.; Kad, B.; Remington, Bruce A.; Wehrenberg, C. E.; Bringa, Eduardo Marcial; Meyers, Marc A.
• Año de publicación: 2016
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Amorphization; Laser Shock Compression; Nano-Twinning; Nanocrystalline; Silicon
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. The nucleation of amorphization is analyzed qualitatively by classical nucleation theory.
Fil: Zhao, S.. University of California at San Diego; Estados Unidos
Fil: Hahn, E. N.. University of California at San Diego; Estados Unidos
Fil: Kad, B.. University of California at San Diego; Estados Unidos
Fil: Remington, Bruce A.. Lawrence Livermore National Laboratory; Estados Unidos
Fil: Wehrenberg, C. E.. Lawrence Livermore National Laboratory; Estados Unidos
Fil: Bringa, Eduardo Marcial. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina
Fil: Meyers, Marc A.. University of California at San Diego; Estados Unidos