Oxidation and Strain in Free-standing Silicon Nanocrystals

Understanding the effects of surface-related strain is important in developing technologies based on nanoscale forms of silicon. This investigation of physical phenomena related to surface oxidation of free-standing silicon nanocrystals (Si-NCs) reveals strongly surface-dependent lattice strain. The time evolution of natural oxidation in air shows a clear correlation between oxide formation and the appearance of compressive strain in a Si-NC's core. Strain is negligible in H-terminated nanocrystals, but increases continuously as oxidation progresses. These results clarify contradicting results in the literature.