Rapid thermal annealing of MeV erbium implanted LiNbO3 single crystals for optical doping

LiNbO₃ single crystals (x cut) were implanted with 3.5-MeV Er ions with fluences up to 3X10¹⁶ cm^-2 Upon annealing the implantation-amorphized surface layer regrows epitaxially, displaying either columnar or planar layer-by-layer growth, depending on the rate at which the samples are brought to the final temperature of 1060°C. Low heating rates (10°C/s) result in columnar regrowth, and 8-h anneals are necessary for complete dissolution of the grain boundaries. In contrast, using a rapid warm-up (100 °C/s), annealing for 1 min at 1060 °C is sufficient to restore a perfect crystal without grain boundaries. The advantage of the short anneal is that it leads to only minimal diffusion broadening of the Er profile. The maximum concentration of optically active Er ions is 0.18 at. %.