Effect of crystal structure on the electrical resistivity of copper-germanium thin-film alloys

Resistivity measurements have been performed on Cu-Ge thin-film alloys with Ge concentration ranging from 0 to 40 at. % in the temperature range 4.2-300 K. It is found that the dependence of resistivity on Ge concentration is not monotonic. This behavior is correlated to changes observed in the crystal structure of the alloys as the Ge concentration is increased. The resistivity is found to remain remarkably low (typically less than 10 μΩ cm at room temperature) over a range of Ge concentration that extends from 25 to 35 at. %, even though above 25 at. % Ge, the alloys consist of the low resistivity ε₁-phase of Cu₃Ge and of a Ge-rich solid solution.