Defect engineering in H and He implanted Silicon

Hydrogen and Helium implanted Si is investigated by electron, optical and atomic force microscopy techniques and x-ray diffraction. In a first moment, the macro-mechanisms of surface blistering and exfoliation were studied as function of the implantation parameters and annealing protocols. Two mechanisms were depicted: i) cracks coalescence and; ii) unstable fracture. The distinct developments were related to microstructure evolutions and discussed in terms of solid mechanics. Particularly, unstable fracture leads to a new method for self-standing Si thin films synthesis via surface delamination. The second moment of the work consists of exploratory experiments revealing unique nanoscopic phenomena. The mechanisms of nanocracks interaction were indentified and modeled under fracture mechanics theory. The elastic interaction between precipitates, giving rise to arranged tridimensional nanostructures was also demonstrated and modeled. This particular result set the basis for further developments in nanostructures architecture within a crystalline matrix showing that strain engineering can provide an affordable way to manipulate precipitates in nanometric scale.

Autorentext

Graduated in Materials Engineering at Universidade Federal do Rio Grande do Sul - Brazil (UFRGS), 2002. Obtained the PhD degree in physics from the Université de Poitiers (France) and in materials science from the UFRGS in 2008. Currently working at the Centre d'Elaboration de Matériaux et d'Etudes Structurales (CEMES/CNRS) in Toulouse, France.