Electrical Conduction in Germanium Grain Boundary Plane

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Abstract
The reduced resistivity and Hall coefficient on the grain boundary in n type germanium bicrystal have been measured over the temperature range about 2.8∼300°K, and the dislocation acceptor level and carrier density in the grain boundary are determined. Experimental results show that the temperature dependence of the mobility may be divided into three regions: In the region of 80∼300°K and 20∼80°K, the mobility µ may be expressed as normal band conduction by the form µ-1=µ l s -1+µ i -1+µ d -1, where the suffices l s, i and d express the contributions to the scattering from the space charge potential well due to the grain boundary, ionized impurities and dislocation, respectively. In particular, the temperature dependence of µ d agrees quantitatively with Dexter and Seitz's theory as a function of dislocation line density. In the low temperature region of 2.8∼25°K, a large and oscillatory negative magnetoresistance is observed and the temperature dependences of reduced Hall coefficient and resistivity have a similar tendency to impurity band conduction in highly doped single crystals.