Photoluminescence of thin films ZrO2 : Er3+ excited by soft X-ray

The photoluminescence (PL) properties and crystalline structure of undoped and erbium ion (Er3+)-doped zirconia (ZrO2) that were prepared by sol-gel methods were examined. The ZrO2 films exhibited a dopant concentration-dependent crystalline phase. As the Er3+ ions' concentration increases, the amount of monoclinic phases of ZrO2 declines. However, the proportion of the tetragonal phase of ZrO2 is enhanced. This fact suggests that Er3+ ions replace the Zr4+ ions and cause the phase transition in the host lattice of ZrO2. Photoluminescence bands were observed by exciting the film at 300 eV with soft X-rays. Experimental results showed that the PL emission bands of Er+3-doped ZrO2 films can be tuned by controlling the Er3+ concentration. In particular, with increasing Er3+ concentration, the blue bands are quenched whereas the green and red bands are enhanced. This phenomenon can be explained as a non-radiative energy transfer.