Application of NRA/channeling to study He(sup +) implanted waveguides

摘要

Four different techniques (RBS/channeling, NRA/channeling, prism coupling, and TRIM) for estimating the depth and width of a damaged layer created by ion implantation in LiNbO(sub 3) are compared. Waveguides can be created in LiNbO(sub 3) by lattice disruption damage with light ions (protons, alphas) or by implantation with Ti. End of range damage results in a decrease in refractive index that acts as a low index barrier to create a waveguide. In the electronic stopping region the ordinary index of LiNbO(sub 3) is decreased while the extraordinary index is increased. The damage in the electronic stopping regime is removed by annealing to a temperature lower than that needed to remove the nuclear damage. RBS/channeling is used to examine displacement of Nb atoms and NRA/channeling is used to study displacement of Li atoms using Li(p,(alpha)) and Li(p,(gamma)) reactions. The authors have analyzed waveguides produced by implantation of 1.7 Mev He(sup +). Comparison of the NRA/Channeling results of as implanted and 175 C and 400 C annealed crystals suggest that electronic stopping induced lattice distortion is responsible for the increase in the extraordinary index in the electronic stopping region.