Two-Dimensional Transport Properties of Germanium Bicrystal at Low Temperature

Two-dimensional properties of grain boundaries in germanium bicrystals are studied at liquid helium temperature ranging from 1.6 to 4.2 K. The experimental results indicate that the magnetoresistivity for 8? tilt angle increases exponentially with the magnetic field intensity square in weak magnetic field and with the linear magnetic field intensity in strong magnetic field. The phenomena are explainable with the percolation theory.