Effects of forming gas annealing on LiNbO3 single crystals

Z-cut congruent LiNbO3 single crystals were annealed in 95%N2+5%H2 at high temperatures. X-ray diffraction showed that 2θ of (0 0 0 6) peak is obviously reduced by 0.6o and 1.0o for the samples annealed at 600 and 900 oC, respectively. A new peak appears at the high-energy side of O 1s spectrum in X-ray photoelelectron spectroscopy (XPS) analyses, and the leakage current is greatly increased. It is proposed that hydrogen is incorporated in LiNbO3 single crystals through forming gas annealing at temperatures up to 900 oC and exists in LiNbO3 as a proton bound to an oxygen ion through O-H bond with its electron donated. -- Research highlights: → A new peak appears at the high-energy side of O1s spectrum in XPS of treated LiNbO3. → The (0 0 0 6) peak of LiNbO3 is shifted by 1o after forming gas annealing at 900 oC. → The leakage current is increased after forming gas annealing.