Photoluminescent and dielectric properties of Eu~(3+)-doped LaAlO_3 thin films fabricated by chemical solution deposition method

摘要

Photoluminescent (PL) and dielectric properties of La_(1-x)Eu_xA1O_3 thin films were investigated in terms of Eu doping content (x=0,0.02,0.04,0.06,0.08, and 0.1) and annealing temperature. The La_(1-x)Eu_xA1O_3 thin films were prepared by a chemical solution deposition method and characterized by X-ray diffraction, field emission scanning electron microscopy, photoluminescence and dielectric measurement. The thin films were dense with a uniform thickness, and showed bright red-orange emissions, originated from the ~5D_0 → ~7F_2 and ~5D_0 → ~7F_1 transitions of Eu~(3+) ions. A stronger emission of ~5D_0 → ~7F_2 than that of ~5D_0 → ~7F_1 was attributed to Eu~(3+)-doping induced structural distortion. The strongest PL intensity was observed in the thin films with a Eu~(3+)-doping content x of 0.06, indicating the existence of concentration quenching effect of photoluminescence. Further lifetime study of photoluminescence indicated that the concentration quenching effect was due to the lifetime decrease of ~5D_0 → ~7F_1 and ~5D_0 → ~7F_2 transitions when Eu~(3+)-doping content x increased. In addition, highly stable dielectric-bias electric field properties of Eu~(3+)-doped LaAlO_3 thin films have been confirmed. Our study suggests that Eu~(3+)-doped LaAlO_3 thin films have potential applications in integrated thin-film optoelectronic devices.