Diffusion and disordering experiments have been conducted on an AlAs‐GaAs superlattice with the impurity (Zn) diffusion‐disordering directed along the layers. Diffusion constants (Zn) and ratios at the low temperature of 575 °C have been determined for the as‐grown AlAs (LB∼140 A˚), GaAs (Lz∼140 A˚), and for the resulting impurity‐induced disordered AlxGa1−xAs (x∼0.5). These results confirm the work of earlier experiments, with normal or perpendicular impurity diffusion into an AlAs‐GaAs superlattice, and for Zn diffusion at 575 °C giveD(AlAs)/D(GaAs)∼350.