Structural studies of erbium-implanted LiNbO 3 single crystals

Abstract

Some LiNbO 3 Y-cut single crystals ((1 0 0) in hexagonal notations) have been implanted with erbium ions and annealed at various temperatures (300, 500 and 1100 °C) for different durations (1, 20 and 100 h). X-ray absorption spectroscopy (XAS) measurements have been then performed at Nb K edge and erbium L III edge in order to provide some information about the structure around the niobium ion of the matrix and the implanted dopant, respectively. A wide angle X-ray spectroscopy (WAXS) study has also been achieved to have some knowledge about the global structure of the Er-implanted layer after annealing. Finally secondary ion mass spectrometry (SIMS) experiments have been carried out to estimate the erbium concentration in the implanted zone after the annealing treatment. The data analysis enables us to conclude that the two annealing temperatures, 500 and 1100 °C, appears like steps as well in the crystallization state of the implanted matrix, as in the local surrounding of the incorporated trivalent rare earth, as in the nature of the solid solutions which appear after the post-implantation annealing treatment. This is probably due to the fact that the Er diffusion strongly increases between 500 and 1100 °C. Indeed, the diffusion coefficient value of the trivalent rare earth is weak for an annealing temperature of 500 °C, while it is high for an annealing temperature of 1100 °C, leading to processes which are governed by kinetic laws in the first case and by thermodynamic laws in the second case.