The influence of triple-junctions upon experimental Ge diffusion profiles (850 to 1000 C) in nanocrystalline Si was investigated using three-dimensional finite element simulations. It was found that triple-junction diffusion was not negligible in nanocrystalline Si made of 40nm wide grains. Ge triple-junction diffusion coefficient could be described by:

D (cm2/s) = 5.72 x 104 exp[-3.24(eV)/kT]

This was approximately 4.7 x 102 times higher than the grain boundary diffusion coefficient, even though diffusion in triple-junction and in grain boundary required a similar activation energy.

Triple-Junction Contribution to Diffusion in Nanocrystalline Si. A.Portavoce, L.Chow, J.Bernardini: Applied Physics Letters, 2010, 96[21], 214102