HIGH-RESOLUTION MAPPING OF 2-DIMENSIONAL LATTICE-DISTORTIONS IN ION-IMPLANTED CRYSTALS FROM X-RAY-DIFFRACTOMETRY DATA

The triple-crystal synchrotron X-ray diffractometry data described by Nikulin, Stevenson, Hashizume, Wilkins, Cookson, Foran & Garrett [J. A ppl. Cryst. (1995), 28, 57-60] has been analyzed to map out two-dimens ional (2D) lattice distortions in silicon (Ill)crystals implanted with B+ ions of 100 keV energy through a periodic SiO2 strip pattern. The lateral periodic structure produced a series of satellite reflections associated with the 111 Bragg peak. The 2D reconstruction incorporates the use of the Petrashen-Chukhovskii method, which retrieves the phas es of the Bragg waves for these satellite reflections, together with t hat for the fundamental. The finite Fourier series is then synthesized with the relative phases determined. Localized distortions perpendicu lar to the surface arising from deposited B+ ions in near-surface laye rs of the crystal are clearly displayed with spatial resolutions of 0. 016 and 0.265 mu m in the depth and lateral directions, respectively. For a sample with the oxide layer removed from the surface, two equall y plausible strain maps have been obtained by assigning relative phase s to 11 satellites using a sequential trial method and a minimum-energ y method. Failed map reconstructions for the oxide-covered sample are discussed in terms of the non-unique solutions of the Petrashen-Chukho vskii phase-recovery algorithm and the ambiguous phases determined for the satellites.