Abstract
Lattice defect and local strain, which were introduced by systematically machining the basal plane of sapphire, ware characterized by cross-sectional transmission electron microscopy (XTEM) and convergent beam electron diffraction (CBED) It was found that dislocations and strain were introduced from the surfaces for all specimens examined in this study. Depths of the introduced dislocations were measured by weak beam dark field (WBDF) method, and residual strain in the vicinity of the surfaces were precisely measured by CBED method using the probe size less than 10nm. The experimental CBED patterns were compared with the calculated patterns to quantitatively evaluate the lattice strain around the surfaces. Maximum penetration depths of the dislocations in the specimens ground with #500 diamond wheel, polished with 4〜8μm and under 1μm diamond slurry were 1.7μm, 700nm and 250nm, respectively. In addition, twin defects were introduced in the specimen ground by #500 diamond to accommodated the large lattice strain during the machining. Residual local strain was found to remain at the depths of 1.0μm, 1.2μm and 300nm for the specimens ground with #500 diamond, polished with 4〜8μm and under 1μm diamond slurry, respectively.
