Three-dimensional interface roughness in layered semiconductor structures and its effect on intersubband transitions

A general model for treating the effects of three-dimensional (3D) interface roughness (IFR) in layered semiconductor structures has been developed and experimentally verified. The configurational average of the IFR potential produces an effective grading potential in the out-of-plane direction, which significantly alters the energy spectrum of the structure. The scattering self-energy of the 3D IFR is also derived. Under strong IFR, this scattering effect is shown to be dominant over phonon interaction and impurity scattering. When applied to intersubband transitions, these theoretical predictions explain the experimentally observed anomalous energy shift and unusual broadening in the intersubband transitions in III-nitride superlattices.