Effect of crystal orientation on defect production and optical activation of Er-implanted sapphire

Abstract

Defect production and optical activity of Er-implanted α-Al2O3 were studied as a function of implanted dose and crystal orientation. Erbium fluences in the range of 8×1013–4×1015 Er+/cm2 were implanted into single crystalline samples with either the m-axis or c-axis normal to the surface. The energy of the Er ions was 200 keV. We found that the number of displaced O atoms was about two times higher on samples with the c-axis normal to the surface compared to the m-samples. The annealing stages of the damage follow a similar behaviour for the m-axis and c-axis samples and the complete recovery occurs for temperatures above 1200°C. The reconstruction of the lattice is accompanied by a reduction in the intensity of the photoluminescence signal above 825°C. Since the amount of Er and its lattice site is maintained, it is concluded that the change on its surroundings was responsible for the decrease of optical activity.