Effects of different ion-implanted dopant species on the solid-phase epitaxy of LiNbO 3 optical waveguides

Abstract

While ion implantation of Ti into LiNbO 3 has been shown to be an effective means of introducing the dopant for the purpose of producing an optical waveguide, oxidation and segregation of the Ti during annealing interferes with the solid-phase epitaxy so that high annealing temperatures are required, approaching 1000° C. Another waveguide dopant, Ag, does not oxidize as readily so that epitaxial regrowth occurs near 400° C, nearly independent of the dopant concentration. However, further annealing near 800° C is required to remove all residual radiation damage from the lattice. In the case of Ag, the mobility at this temperature is sufficiently high that the dopant diffuses into the substrate, destroying the dopant concentration profile. Pb exhibits an epitaxial regrowth behavior that is intermediate to Ag and Ti, with a mobility at 800° C that does not significantly alter the concentration profile. However, even after annealing at 900 ° C, Pb exhibits negligible substitutionality in the lattice.