Secondary ion mass spectrometry study of erbium diffusion in lithium niobate crystals

A systematic investigation of erbium diffusion in lithium niobate (LiNbO₃) crystal as a function of crystal cut-direction, diffusion process parameters (temperature and time), and initial film thickness is reported. Depth concentration profiles of erbium are obtained by secondary ion mass spectrometry (SIMS). Combining experimental data with diffusion theory, the relevant diffusion parameters are derived. Diffusion from an infinite source of erbium ions is studied to evaluate the solid solubility lower limit of Er in LiNbO₃. A thin film diffusion regime, with complete depletion of ion source, is also investigated. A comparison of Er diffusion with Er/Ti codiffusion in LiNbO₃ crystals is reported.