The influence of temperature and magnetic and electric fields on the grain boundary longitudinal conductance, σ, at low temperatures in Hg-doped polycrystals and bicrystals of Ge was studied. It was shown that the σ(T), σ(E) and σ(H) dependences for grain boundaries in bicrystals were determined by metallic and hopping mechanisms, whereas a hopping channel in bicrystalline samples could not be found. The behaviour of the σ(H) dependences for low magnetic fields (super-linear) and the linearity of the current–voltage characteristics at T < 100K indicate merely the presence of a metallic mechanism in bicrystalline samples. All of the results obtained indicate that during the zone-melting process, the segregation of impurities at grain boundaries develops differently in bicrystalline and polycrystalline ingots.

Metallic and Non-Metallic Longitudinal Conductance of Grain Boundaries in Bicrystalline and Polycrystalline Germanium Doped with Mercury and Antimony. A.K.Fedotov, A.V.Mazanik, T.Figielski, A.Makosa, Y.M.Ilyashuk: Journal of Physics - Condensed Matter, 2002, 14[48], 13111-7