Incident-Angle Dependence of Catastrophic Dechanneling for Strained-Layer Superlattices

A strong asymmetry has been observed in the angular dependence of the catastrophic dechanneling depth in strained-layer superlattices. This new effect occurs under resonance conditions, where the wavelength of the planar-channeled particles equals the period of the superlattice, and is demonstrated for {110} planar channeling in $\mathrm{GaP}/\mathrm{Ga}{\mathrm{As}}_x{\mathrm{P}}_{1-x}$. A theoretical, phase-plane analysis shows that the angular tilt required for shifting of the catastrophic depth by one layer is a direct measure of the strain in the first few layers.