Influence of annealing temperature on the luminescence of Er/Yb co-doped Al2O3 films

The influence of annealing temperature on the photo-luminescence (PL) of high concentration Er/Yb co-doped Al2O3 films was studied. The relationship between PL spectra and microstructure of the films at various annealing temperatures was revealed by analyzing the dependence of the intensity and the full width at half-maximum of the PL spectra (in the annealing temperature. The PL measurement shows that the annealing behavior may be split into three different regimes. Below 750 degrees C, the intensity increases with the increase of annealing temperature with a small slope, which corresponds to the amorphous Al2O3 films. Between 800 degrees C and 900 degrees C, the PL intensity increases considerably, where the microstructure of the Mints was identified to be composed of gamma-Al2O3 grains in nano-meter scale; At the temperature of 1000 degrees C, the intensity of PL spectrum decreased to a very low level, gamma-Al2O3 grains and the segregation of Er2O3 and Yb2O3 phases were observed by using transmission electron microscopy. Furthermore, the dependence of PL spectrum shape on the PL intensity of sub-level transition was analyzed and discussed by fitting the PL spectra at various temperatures.