Secondary ion mass spectrometry and Auger study of lithium niobate processing for integrated optics

The impurities introduced into lithium niobate crystals by diffusion furnaces typically used for Ti:LiNbO3 integrated optical devices are probed using semiquantitative surface Auger analysis and secondary ion mass spectrometer (SIMS) depth profiling. It is shown that reactions in silica furnaces that accompany aging or contamination by lithium niobate result in the transfer of large amounts of silica to the crystal surfaces. High purity alumina furnaces can result in surface layers of 0.2–0.6 at. % sodium. Many common crystal cleaning methods should be adequate for the processing of lithium niobate optical waveguides.