Effects of forming gas annealing on LiNbO3 single crystals

Z-cut congruent LiNbO3 single crystals were annealed in 95%N-2+5%H-2 at high temperatures. X-ray diffraction showed that 2 theta of (0 0 0 6) peak is obviously reduced by 0.6 degrees and 1.0 degrees for the samples annealed at 600 and 900 degrees C, 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 degrees C and exists in LiNbO3 as a proton bound to an oxygen ion through O-H bond with its electron donated. (C) 2010 Elsevier B.V. All rights reserved.