Evaluation of the Quality of Sapphire Using X-ray Rocking Curves and Double-Crystal X-Ray Topography.

摘要

Single-crystal sapphire is a material with a wide range of applications as a result of its unique physical, optical, mechanical, and chemical properties. The quality of a sapphire crystal can influence its effectiveness in many applications. High-quality, near-perfect, single-crystal sapphire can be grown, but it is difficult to shape and polish because of its extreme hardness, and surface flaws and damage are commonly produced during fabrication. Since this damage may exist in a buried subsurface layer, it can be difficult to detect. X-ray rocking curves and X-ray topography are extremely sensitive to the level of defects and strains in single crystals. A number of sapphire substrates, from several suppliers were examined using these techniques in order to determine how applicable they are for detecting defects in sapphire. A wide range in quality was found in sapphire received from different suppliers. Residual grinding/polishing damage was observed in many samples. Other defects observed included dislocations and mosaic structure and twinning in lower quality material. Rocking curves and double-crystal X-ray topography appear to be simple techniques for evaluating and determining the quality of sapphire. In particular, they are sensitive to subsurface damage and microscopic defects can be imaged at low to moderate magnification. Sapphire, X-ray diffraction, Crystal defects.