X-ray diffraction of ion-irradiated diamond, silicon and germanium

Diamond, Si and Ge powders were irradiated by 3 MeV Ne, Ar, Kr and Xe ions. The (111) X-ray diffraction line of diamond broadened and shifted toward lower angles approaching a limiting value with increasing ion fluence. This is consistent with a model involving dynamic equilibrium between production and radiation annealing of defects. Saturation values of diamond lattice parameter expansions increased with increasing ion mass. A volume increment per defect of about 23% of the atomic volume was derived. The X-ray diffraction lines of Ge did not broaden or shift significantly but decreased in intensity with increasing ion fluence, consistent with the Morehead-Crowder model. The damaged Ge recovers completely after annealing for 30 min at 7500K in air. Si appears to undergo radiation annealing to a greater extent than Ge under the same conditions of irradiation. (author)