Dechanneling of MeV protons by 60° dislocations

This paper describes a model for interpreting experimental transmission ion channeling results for dechanneling by 60^∘{} misfit dislocations in epitaxial Si_1-x{Ge}ₓ$/Si material in terms of rotated lattice planes of the ${Si}_{1{{-}}x}Geₓ epilayer with respect to the silicon substrate. A Monte Carlo channeling simulation program is used to model the trajectories of the incident MeV protons through the epilayer and the thinned Si substrate in order to calculate the average transmitted proton energy as a function of the sample-tilt angle about the beam axis and the effective rotation angle of the epilayer. The conditions under which the 60^∘{} dislocations can be resolved from the surrounding perfect crystal and also resolved from adjacent 60^∘{} dislocations causing a slightly different amount of lattice plane rotation are discussed using this model. Good agreement is demonstrated with experimental results showing the variation in transmitted proton energy across a group of five 60^∘{} dislocations for different sample-tilt angles.