CHARACTERIZATION OF MICROGRAVITY AND GROUND-BASED GROWN CRYSTALS USING SYNCHROTRON WHITE BEAM X-RAY TOPOGRAPHY AND HIGH RESOLUTION TRIPLE AXIS X-RAY DIFFRACTION

The combination of Synchrotron White Beam X-ray Topography (SWBXT) and High Resolution Triple Crystal X-ray Diffractometry (HRTXD) has been used to non-destructively diagnose defect structures in single crystals grown in both microgravity and ground-based environments. Due to the fact that SWBXT is the superior technique for the characterization of defects in highly perfect regions and HRTXD is superior for highly imperfect regions, the combination of these two complementary techniques can provide a sensitive and useful tool to quantitatively analyze defect structures. Microgravity grown CdZnTe and ground-based grown ZnSe and ZnTe have been studied using this combination of techniques. The analysis from CdZnTe crystals revealed that the defect structures were dependent on the local cooling rates, the lower defect density regions being obtained at the slower cooling rates. SWBXT studies on ZnTe revealed a cellular structure of dislocations while HRTXD analysis revealed multiple surface streaks, which indicated mosaic blocks separated by small misorientations. Studies on the surface quality of ZnSe crystals revealed similar results from both SWBXT and HRTXD. This study indicates that SWBXT and HRTXD analytical results can not only be correlated but can also provide a complementary view of defect structures.