Nanometric size effect on Ge diffusion in polycrystalline Si
The nanosize effect on Ge diffusion (850 <= T <= 1000 degrees C) in polycrystalline Si layers is investigated. The Ge diffusion coefficients in microcrystalline and nanocrystalline Si layers made of 30 mu m and 40 nm wide grains, respectively, are measured and compared. In the microcrystalline Si layer, the Ge diffusion coefficient in micrograin boundaries is measured using a conventional analytical solution of Fick's equations corresponding to the Fisher model. In the nanocrystalline Si layer, the Ge diffusion coefficients in nanograins and in nanograin boundaries are measured via a method based on two-dimensional simulations using the Fisher model geometry. The diffusivities in nanograins and nanograin boundaries are one order of magnitude higher than in micrograins and micrograin boundaries, respectively. However, the nanosize effect appears to be different in grains and grain boundaries; despite that the activation energy for diffusion in 40 nm wide grains is at least 1 eV lower than in Si bulk. The activation energy in nanograin boundaries is about the same as in micrograin boundaries.
Journal of Applied Physics
"Nanometric size effect on Ge diffusion in polycrystalline Si" (2008). Faculty Bibliography 2000s. 849.