Photovoltaic fields and the secondary structure of nominally pure lithium niobate crystals grown from a boron-doped furnace charge

It has been shown that the growth of nominally pure lithium niobate crystals from a nonmetal (boron)-structured melt makes it possible to control the secondary phase, optical homogeneity, photoelectric fields, and bandgap of the material. From the characteristics of photoinduced light scattering, the photovoltaic and diffusion field strengths in nominally pure LiNbO$_{3}$:В crystals have been determined. It has been shown that the diffusion field governing the concentration of shallow electron traps in LiNbO$_{3}$:В crystals is between diffusion fields in crystals having a congruent and stoichiometric composition and depends on boron concentration in the charge. It has been found that the bandgap in LiNbO$_{3}$:В crystals is the same as in the stoichiometric crystal but the optical homogeneity of LiNbO$_{3}$:В crystals is closer to that of the congruent crystal. In addition, the concentration of OH groups in LiNbO$_{3}$:В crystals is lower and their arrangement in the structure is more regular than in the congruent crystal.