Interference of bulk and boundary scattering in films with a quantum size effect

The interference between boundary and bulk scattering processes is analysed for ultrathin films with random rough walls. The effective collision and t ransport relaxation times for scattering by random bulk and surface inhomog eneities are calculated, when possible analytically, in quantum size effect conditions. The transport and localization results are expressed via the b ulk transport parameters and statistical characteristics of the surface cor rugation. The diagrammatic calculation includes second-order effects for bo undary scattering and full summation for bulk processes. The interference c ontribution is large in systems with robust bulk scattering and can be comp arable to, or even exceed, the pure wall contribution to the transport coef ficients.