在Sapphire 基材上以電化學沉積YAG 螢光薄膜

摘要或動機

A novel method of electrolytic Y₃Al₅O₁₂ (YAG:X, X=Ce, Eu, Tb) phosphor thin-film coating on sapphire was investigated in yttrium, aluminum, cerium, europium and terbium nitrate solution. By means of X-ray diffraction (XRD), scanning electronic microscopy (SEM) observation, and cathodic polarization tests, the most efficient potential of deposition was found in the region between -1.2 V~-1.5 V. The YAG phosphor thin-film was successfully synthesized by the cathodic deposits were heat-treated at 1200 ℃ for 4 hours. The excitation photoluminescence (PL) spectra of Ce³⁺ in YAG consists of a strong maximum at about λ＝520~530 nm that show yellow emission peak, and a red emission was observed at about λ＝595~700 nm by additional Eu³⁺. The excitation PL spectra monitored inλ＝480~500 nm with the amount of Tb³⁺ and that show green emission peak. The fabrication of YAG phosphor thin-film will be useful to improve the emission intensity of the white LEDs in the future.由電解沈積陰極的電位—電流關係圖、Ｘ光繞射分析、SEM 觀察及實驗反應的經驗式我們可以知道要在導電的sapphire（氧化鋁單晶）基材上電解沈積合成燒結YAG 螢光薄膜所需之各類氫氧化金屬，其合適的電解沈積電位為-1.2 Ｖ~-1.5 V，我們利用電化學沈積法可以成功地合成欲燒結成YAG 螢光薄膜所需之氫氧化金屬，將所合成之氫氧化金屬放入高溫爐以1200 ℃高溫燒結4 小時後，依據我們目前以光螢光激發(PL)這些YAG 薄膜的光譜結果，可以成功地得到YAG:Ce(λ=520~530nm)黃光螢光薄膜、YAG:Eu(λ=595~700nm)紅光螢光薄膜及YAG:Tb(λ=480~500nm) 綠光螢光薄膜，證明以新的電化學方法可以成功製備YAG 螢光薄膜，相信這些研究成果未來應用在研發提昇白光LED 發光效能上有極大之助益。