退火对磁控溅射掺铕氧化钇薄膜光致发光谱的影响

doi:10.3964/j.issn.1000-0593(2020)11-3336-05

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Abstract Fluorescent performance of rare earth doped luminescent film is closely related to post-annealing treatment. In order to explore the influence of thermal annealing on luminescence and structure of Y₂O₃∶Eu³⁺ thin films prepared by magnetron sputtering, three groups of the films with thickness of 100～150 nm were deposited on silica glass substrates under three different conditions respectively. Each group contained four samples, which were prepared under the same condition and annealed respectively at room-temperature, 700, 900 and 1 100 ℃ for 2 h in O₂ ambience. The measurements of X-ray diffraction spectra (XRD), electron energy dispersion spectra (EDS) and photoluminescence spectra（PL）were conducted on the films, and the results were summarized as follow: Although the Y₂O₃∶Eu³⁺ thin films prepared under different sputtering conditions, the annealing effects on these films are found to be similar if they experience the same annealing process. Firstly, the PL excitation spectra indicate that charge transfer mechanism is responsible for the luminescence of all the films, and the characteristic wavelength (~252 nm) corresponding to this mechanism does not vary with the annealing temperature. Secondly, annealing treatment at 700 ℃ cannot significantly improves the crystallinity and the light emission intensity of the films. When annealing temperature reaches 900 ℃, the annealed film contains cubic phase Y₂O₃∶Eu³⁺ nanocrystallites, leading to the main peak at 612 nm enhanced significantly. However, as the temperature increased to 1 100 ℃, a phase transition from cubic to monoclinic occurs, and the film structure is dominated by the monoclinic phase. Although the content ratio of Eu to Y in the film is decreased to 0.05% after being annealed at 1 100 ℃, the light emission efficiency increases obviously. This result is ascribed to an improved crystallinity and a fact that there are more sites with anti-inversion symmetry in monoclinic lattice than in cubic one. In this case, not only is the red-light emission stronger, but also the main peak is shifted to 623 nm, which represents the characteristics of electric dipole transition ⁵D₀→⁷F₂ in monoclinic structure. Meanwhile, the luminescences from magnetic dipole transition ⁵D₀→⁷F₁ and electric dipole transition ⁵Ｄ₀→^F₀ are enhanced compared with those in cubic lattice. Especially for the ⁵D₀→⁷F₀, the intensity contrast between these two structures indicates obviously that the 581nm emission can be assigned to monoclinic phase Y₂O₃∶Eu³⁺ crystalline. This work demonstrates the features of the annealing effect on magnetron sputtering Y₂O₃∶Eu³⁺ thin film, and an alternative method for preparing Y₂O₃∶Eu³⁺ film with high luminescence efficiency, as well as the PL spectrum evolution induced by the phase transition from cubic to monoclinic.

Key words：Y₂O₃∶Eu³⁺; Photoluminescence; Annealing; Monoclinic; Sputtering

Received: 2019-08-05 Accepted: 2019-12-22

ZTFLH:

O433.4

Corresponding Authors: YU Yun-peng E-mail: ypyu@stu.edu.cn

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)11-3336-05 OR https://www.gpxygpfx.com/EN/Y2020/V40/I11/3336