Selective-Area Repoling of Single-Crystalline LiTaO3 and Its Characterization.

Selective-area repoling (SARP) of single-crystalline LiTaO3 has been investigated. SARP is impossible at room temperature, whereas single-domain inversion can occur. At high temperatures, SARP is completed under the applied field of 12 kV/mm at 190°C, which is almost the same condition as that required for single-domain inversion. By fitting the SARP current to the Avrami theory, it is deduced that a sidewise growth mechanism is dominant in the process. A few kinds of metal in the electrode and surface contamination can diffuse into LiTaO3 during SARP and thus affect the charge density and convergence time, i.e., the progress of SARP. Transmission electron microscopy has revealed the domain structure, the lattice defect and the single-domain capping layers that have positive surface charge on both the front and back. Inverted microdomains formed in the capping layer do not easily grow and coalesce into single domains and remain after the SARP process.