Raman-scattering elucidation of the giant isotope effect in hydrogen-ion blistering of silicon.
In this work, we investigate the origin of a giant isotope effect discovered in the blistering of hydrogen-ion-implanted and annealed silicon. Si(001) samples were implanted or co-implanted with 5 keV of H and/or D ions to total fluences of 2 x 10(16) and 6 x 10(16) ion/cm(2). The lower fluence is sufficient for blistering by pure H, but the higher one is required for the maximum blister coverage whenever D is involved. On these samples, we carried out Raman-scattering investigations of the evolution of Si-H/D complexes upon a stepwise thermal annealing from 200 to 550 degrees C. We have identified the critical chemical transformations characterizing the hydrogen-deuterium-induced blistering of silicon. The puzzling dependence on ion mass appears to be mainly connected with the nature of the radiation damage. We have found that H is more efficient in "preparing the ground" for blistering by nucleating platelets parallel to the surface, essentially due to its ability to agglomerate in the multihydride monovacancy complexes that evolve into hydrogenated extended internal surfaces. By contrast, D is preferentially trapped in the surprisingly stable monodeuteride multivacancies.
Strain in Hydrogen-Implanted Si Investigated Using Dark-Field Electron Holography
The microstructure of ion-implanted crystals is profoundly dictated by mechanical strain developing in interplay with structural defects. Understanding the origin of strain during the early stages of development is challenging and requires accurate measurements and modeling. Here, we investigate the mechanical strain in H-implanted Si. X-ray diffraction analysis is performed to measure the mesoscopic out-of-plane strain and dark-field electron holography to map strain in two-dimensions (2D) with nanometer spatial resolution. Supported by finite element method modeling, we propose that the mean strain field is explained by overlapping and averaging discrete strain fields generated by sub-nanoscopic defects that are intimately related to the H depth concentration.
What is Enlightenment
Enlightenment is man's emergence from his self-imposed nonage. Nonage is the inability to use one's own understanding without another's guidance. This nonage is self-imposed if its cause lies not in lack of understanding but in indecision and lack of courage to use one's own mind without another's guidance. Dare to know! (Sapere aude.) "Have the courage to use your own understanding," is therefore the motto of the enlightenment.