APPLICATION OF NRA CHANNELING TO STUDY HE+ IMPLANTED WAVE-GUIDES/

Four different techniques (RBS/channeling, NRA/channeling, prism coupl ing, and TRIM) for estimating the depth and width of a damaged layer c reated by ion implantation in LiNbO3 are compared. Waveguides can be c reated in LiNbO3 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 crea te a waveguide. In the electronic stopping region the ordinary index o f LiNbO3 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/c hanneling is used to examine displacement of Nb atoms and NRA/channeli ng is used to study displacement of Li atoms using Li(p,alpha) and Li( p,gamma) reactions. We have analyzed waveguides produced by implantati on of 1.7 MeV He+. Comparison of the NRA/channeling results of as impl anted acid 175 degrees C and 400 degrees C annealed crystals suggest t hat lithium movement towards the nuclear damage region is responsible for the increase in the extraordinary index in the electronic stopping region.