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

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Abstract
Diamond, Si and Ge powders were irradiated by Ne, Ar, Kr and Xe (3 Mev) ions up to tluences ot ∼ 200 ions/nm2. As reported for fast-neutron irradiation, diamond undergoes structural damage with heavy ion bombardment. The (111) X-ray diffraction line was observed to broaden and shift toward lower angles; the lattice parameter expansions were correlated with the displacement damage component of the energy of the bombarding ions. The X-ray line shifts apparently approached asymptotically limiting values with increasing ion fluences (10–30 ion/nm2), consistent with a model involving dynamic equilibrium between production and radiation annealing of the defects. The saturation lattice parameter shifts increased with increasing ion mass. A volume increment per defect of (1.3 ± 0.2) × 10−3 nm3 was derived which is about 23% of the atomic volume. The X-ray diffraction lines of Ge did not shift or broaden significantly with ion irradiation but decreased in intensity with increasing ion fluence, consistent with the Morehead-Crowder model. The metamict damage cross-section of Ge to argon (3 MeV) ions is 0.35 ± 0.05 nm2- and 1.0 ± 0.2 nm2 for Kr (3 MeV) ions. The damaged Ge recovers completely after annealing for 30 min at 750 K in air. Silicon has a damage cross-section of 0.15 ± 0.10 nm2 for Kr (3 MeV) ions, and appears to undergo radiation annealing to a greater extent than Ge under the same conditions of irradiation.

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