Resonance dechanneling in strained-layer superlattices in the case of axial-to-planar channeling transition

Resonance effects are reported for the axial-to-planar channeling transition in strained-layer superlattices (SLSs). The resonance dechanneling effect observed occurs when the wavelength of the transverse ion motion amounts to a multiple of the distance between the atomic strings forming the planes. This resonance phenomenon is more pronounced in SLSs than in simple single crystals. A general theoretical description of planar channeling in layered structures is presented which takes into account the influence of the periodic action of individual atomic strings and of the alternating tilts of crystallographic directions on off-normal ion channeling in SLSs. The structure of the planar channels is taken into consideration by an analytical expression for the atomic plane potential in the string of string model in the Thomas-Fermi-Moliere approximation. The results of numerical integration of the general equation of motion are in good agreement with experimental and computer simulation results. The calculated energy dependence of the dechanneling shows clearly that, in contrast to the catastrophic dechanneling, the resonance dechanneling is a purely nonlinear effect. (orig.)