Photoluminescence and structural studies of Tb and Eu implanted at high temperatures into SiO2 films

The present work deals with the photoluminescence (PL) emitted from Eu and Tb ions implanted at room temperature (RT) up to 350 °C in a SiO2 matrix, followed by a further anneal process. The ions were implanted with energy of 100 keV and a fluence of 3×1015 ions/cm². Further anneals were performed in atmospheres of N2 or O2 with temperatures ranging from 500 up to 800 °C. PL measurements were performed at RT and structural measurements were done via transmission electron microscopy (TEM). In addition, the Rutherford backscattering technique (RBS) was used to investigate the corresponding ion depth profiles. For Tb, the optimal implantation temperature was 200 °C, and the anneal one was of 500 °C. Under these conditions, the PL yield of the sharp band centered at 550 nm was significatively higher than the one obtained with RT implants. The PL spectra corresponding to the Eu ions show two bands, one narrow centered around 650 nm and a second broad one in the blue–green region. The implantation temperature plays a small influence on the PL shape and yield. However, the annealing atmosphere has a strong influence on it. Samples annealed in N2 present a broad PL band, ranging from 370 up to 840 nm. On the other hand, the O2 anneal conserves the original as-implanted spectrum, that is: a broad PL band in the blue–green region together with sharp PL band in the red one. For both ions, Tb and Eu, the TEM analyses indicate the formation of nanoclusters in the hot as-implanted samples.