Hafnia-based Luminescent Insulator for Phosphor Applications

Pure and doped hafnia-based films were fabricated by RF magnetron sputtering and their microstructure, optical and luminescent properties were investigated versus annealing treatment. It was observed a phase separation in Si-rich-HfO2 films at 900-1100 degrees C resulted in the formation of HfO2 and SiO2 phases, as well as pure silicon clusters. A light emission in the orange-red spectral range was observed from Si-rich-HfO2 samples contrary to their pure counterparts. The correlation of the peak position of red photoluminescence with silicon cluster sizes allowed gives the evidence of the carrier recombination in silicon clusters. The comparison of Er-doped-HfO2 and Er-doped Si-rich-HfO2 films showed an enhancement of rare-earth emission efficiency due to an effective energy transfer from Si-clusters.