Fracture origins in LiNbO3 wafers due to postprocessing micro-repolarization

In the process of developing electro-optic devices from ferroelectric z-cut LiNbO3 wafers, a repolarization throughout the wafer thickness occurs due to a localization of electric charges on the wafer. The repolarization not only generates microdomains causing light to scatter but also large defects in the crystal that become the origin of wafer fracture. The size of such defects is comparable to the wafer thickness (0.5 mm), and an anomaly in th e chemical and crystalline structures can be found in them. X-ray diffracto metry and x-ray photoelectron spectroscopy confirm that a chemical reductio n in the defective region occurs.