Abstract Hall measurement has been carried out for a set of n-type Ge-like Ge 1− d -Si 2 single crystal alloys (up to ∼ 12 at%Si). From the Hall mobility data, an expression for alloy and phonon scattering is derived for electrons. The effect of alloy scattering in the electron mobility is found from temperature dependence as μ dis∼T −0.5 α(1−α) as is shown from the Brooks theory. The cross section for scattering by phonon increases with the Si concentration in the crystal. This effect is consistent qualitatively with the virtual crystal model.