The solubility and diffusion of Co in extrinsic material at 700C was investigated by using radiotracer measurements. It was found that the solubility was enhanced by B or P doping, and that this was accompanied by a decrease in the diffusivity which was a factor of 3 smaller than that in intrinsic material with 8 x 1019B/cm3 and 3500 times smaller in material with 1020P/cm3. Mossbauer spectra from the latter sample showed that the Co occurred as two species, Cos and CosP, and the effect of this upon P-diffusion gettering was explained. In B-doped material, the diffusion coefficient decrease could be explained by the reaction of Coi+ and B, and a single donor level of Coi at Ev + 0.15eV was deduced.

D.Gilles, W.Schröter: Materials Science Forum, 1986, 10-12, 169-74