The diffusion of Co, Fe and Cr in monocrystalline material was found to be a rapid process at semiconductor-device fabrication temperatures. Electronic-grade Ge samples were coated with a radioactive surface source and short-term annealed in a lamp furnace at 600 to 900C. The diffusion coefficients (figure 2) were determined from the penetration profiles of the radioisotopes, 57Co, 59Fe and 51Cr and could be described by the expressions:

Co:     D (cm2/s) = 7.3 x 102 exp[-2.00(eV)/kT]

Cr:     D (cm2/s) = 3.8 x 10-4 exp[-0.71(eV)/kT]

Fe:     D (cm2/s) = 1.9 x 10-1 exp[-1.22(eV)/kT]

The results were interpreted within the framework of interstititial-substitutional diffusion.

Radiotracer Diffusion of Cobalt, Iron and Chromium in Dislocation-Free Germanium. L.Lerner, N.A.Stolwijk: Applied Physics Letters, 2008, 93[3], 032107

Table 4

Diffusivity of Be in Ge