Defect analysis on Al2O3:Cr single crystals using Dark Field X-ray Microscopy

High quality sapphire (Al2O3) single crystals are important as the application range is broad, e.g. substrates for microelectronics and watch windows. However, defects are often present in sapphire crystals, especially when doped, e.g. with Cr. A deeper understanding of the origin of these defects is essential to develop strategies to grow high quality, defect free single crystals. We have previously found for ruby fibers (Al2O3:Cr), that different defects like bubbles, precipitates and inhomogeneity bands seem to be related, leading to the assumption of interactions between these defects and their formation. DFXM is a tool for mapping the crystal structure and lattice stresses. The spatially resolved data from this study will provide valuable insights about the local composition by applying Vegard's Law. In combination with the residual stress, this will deepen the understanding of defect formation and can provide strategies for improving single crystal growth of sapphires and rubies.