“…In fact, according to the literature, a low degree of interdiffusion is common in Si/Ge superlattices. [48][49][50] The composition heterogeneities would change the mass density depthdistribution but the total thickness of a set of Si/Si 1−x Ge x /Ge/ Si 1−x Ge x layers would be kept constant. The result is accurately simulated KFs, i.e., no simulated fringes would be out-of-phase with respect to the experimental ones because the total thickness is maintained, while affecting the KF and SL overall intensity.…”