Anti-Bragg quantum well structures as a tool for the investigation of vertical disorder

We present a novel approach to the investigation of vertical disorder in qu antum wells (QW) based on the reflectivity lineshape analysis of anti-Bragg structures, where the condition of destructive interference makes the refl ectivity spectrum extremely sensitive to vertical disorder. We exploit the method in the case of GaAs/AlGaAs structures and we demonstrate the possibi lity of measuring very small differences in the excitonic transitions.