Extended x-ray absorption fine-structure investigation ofNb3Ge films

We have studied the extended x-ray absorption fine structure (EXAFS) on the Ge $K$ edge in ${\mathrm{Nb}}_3$Ge ($A15\mathrm{}$ structure) films with samples prepared by the chemical-vapor-deposition and $e$-beam coevaporation techniques and having different superconducting transition temperatures. For the $e$-beam samples, our EXAFS experiments confirm the existence of two phases, one of which is quasiamorphous with smaller atomic separations and average coordination number than the $A15\mathrm{}$ phase. The additional temperature dependence of the fluctuations in the nearest- (and further-) neighbor distance agrees with expectations from the phonon spectrum determined by other methods. No effect of any lattice transformation between 77 and 573 K was obtained.