The diffusion coefficient of Si in crystalline Ge between 550 and 900C was determined. A molecular beam epitaxially grown buried Si layer in an epitaxial Ge layer on a crystalline Ge substrate was used as the diffusion source. For samples annealed at above 700C, a 50nm-thick SiO2 cap layer was deposited in order to prevent decomposition of the Ge surface. The temperature dependence of the diffusion coefficient could be described by:

D (cm2/s) = 4.2 x 101 exp[-3.32(eV)/kT]

over the entire temperature range. These data extended previous measurements by 2 orders of magnitude at low temperatures.

H.H.Silvestri, H.Bracht, J.Lundsgaard Hansen, A.Nylandsted Larsen, E.E.Haller: Semiconductor Science and Technology, 2006, 21, 758-62