Synchrotron X-ray reticulographic measurement of lattice deformations associated with energetic ion implantation in diamond

A natural diamond plate of thickness 0.55 mm, polished parallel to (110), c ontained a dislocation-free and unusually distortion-free area into which a beam of fluorine ions of 17 MeV energy had been injected. The beam, the di ameter of which was pinhole-limited to similar to 3/4 mm, produced a radiat ion-damaged layer at similar to 5 mu m depth and uplifted the crystal above to form an optically detectable mesa. Conventional X-ray topography regist ered lattice distortion strongly at the mesa periphery, but did not disclos e the deformation of nearsurface lattice layers at the mesa centre. In cont rast, reticulography showed directly that the central surface lattice layer s were slightly domed outwards. (In reticulography, a fine-scale X-ray abso rbing mesh placed between a Laue-reflecting crystal and the topograph-recor ding plate splits the diffracted beam into individually trackable microbeam s, the direction differences of which are measured by recording them at dif ferent mesh-to-plate distances.) Reticulographs were recorded in back-refle ction, 2 theta(B) = 135 degrees, using both symmetric reflection from the ( 110) surface, reflection 440 dominant, with lambda = 0.116 nm, and reflecti on 33 (1) over bar, with lambda = 0.151 nm. The metrological procedures and geometrical analysis applied are described. The central surface curvature was derived from ten reticulographs recorded under different conditions, wh ich tested the reproducibility of the method. Deviations of individual radi us values from the mean were similar to 4% for both curvature in (001) and orthogonally in (110), the overall mean being 5 m. Two-beam optical interfe rometry failed to measure this curvature.