Optical Properties of CuCl⁺-Implantation and Observation of Sub-micrometre Particles in α-Al₂O₃ Crystals

Crystal samples of α-Al₂O₃ were implanted in different crystalline orientations with CuCl⁺ at intensities from 6×10¹⁶ ions/cm² to 5×10¹⁷ ions/cm² and energies from 350 to 380keV at different temperatures. A strong absorption of UV section can be seen in optical absorption spectra for all of the specimens. Gaussian fitting for the absorption curves with luminescence measurements confirmed that there were point defects such as F, F⁺, F₂⁺, and F₂ centres in the CuCl⁺-implanted α-Al₂O₃ samples. It is found that the absorption intensity is decreased by annealing treatment, thus the number of the colour centres was decreased due to annealing. It is also found that the variety of colour centre number was dependent greatly on implantation conditions, substrate orientation and annealing temperature. Sub-micrometre particles after annealing have been observed by using the SEM technique.