摻雜YAG螢光粉之奈米結構氧化鋅的光電特性研究

現今所使用的白光LED大多採用藍光晶片激發黃色螢光粉，但因為螢光粉塗佈不均會導致色彩分佈不均勻的光暈現象，為了得到更高均勻性的白光光源，本論文提出一種新穎的螢光粉分佈結構，藉由超音波噴霧法將YAG:Ce3+螢光粉摻雜於n型氧化鋅(ZnO:YAG)材料中，以探討此螢光材料的晶體結構與發光性質。　　實驗結果顯示，未摻雜的氧化鋅呈現六角板結構，[0002]優選方向垂直於基板；而隨著摻雜濃度的提升，會致使ZnO:YAG薄膜的生長機制受到改變，造成六角板的側向成長速率加快，導致(0002)有偏折的現象；當摻雜濃度持續增加，偏折程度會逐漸變大，致使ZnO:YAG薄膜呈現奈米花結構。經由XRD繞射圖得知，摻雜濃度提昇會使結晶品質變差，半高寬變大。在PL激發光譜上，可以觀察到ZnO有很強的近能隙發光，峰值約為380 nm；伴隨著摻雜比例提升，ZnO的缺陷發光與YAG:Ce3+的螢光也隨之增加；其中，YAG:Ce3+的螢光峰值位於540 nm，是由於電子從激發態5d躍遷回基發態4f所激發的螢光。由吸收邊緣圖得知，氧化鋅的吸收能隙隨摻雜濃度提升而紅移，是由於缺陷密度隨摻雜濃度提升而增加，導致發光特性變差。　　製作n-ZnO:YAG/p-Si元件，並於p型矽基板上製作鎳/銀(Ni/Ag)合金之電極，使接面達歐姆接觸；其I-V曲線呈現二極體之整流特性，且起始電壓Vth約為5V；於PL光譜上可觀察到YAG:Ce3+之峰值，且元件受光子激發後，呈現紫白光。

關鍵字

氧化鋅； YAG螢光粉；噴霧熱解法；光激發螢光

並列摘要

Nowadays, the white light emission diode (LED) most adopts blue chips to excite yellow phosphor. However, uneven phosphor coating results in the phenomenon of uneven color distribution. In order to get higher quality of white light source, the thesis proposes a novel structure of phosphor coating. It adopts ultrasonic spray pyrolysis to doped YAG:Ce3+ phosphor into zinc oxide (ZnO:YAG) to discuss about the crystal structure and luminescence properties of fluorescent material. 　　The results of the experiment show that undoped ZnO appears in the structure of hexagonal plate. It indicates an excellent crystalline along the (002) preferred orientation. With the increasing doping concentration, it would change the growth mechanism of ZnO:YAG films. Then, it results in accelerating lateral growth rate of hexagonal plate. It's the phenomenon of deflection of hexagonal plate. As the doping concentration increasing gradually, the degree of deflection would get much bigger. It results in ZnO:YAG film appearing in the structure of nanoflower. According to the XRD patterns, the increasing doping concentration would make the crystal quality deterioration and make FWHM larger. 　　Photoluminescence measurements revealed that ZnO is with stronger near-band-edge and peak value is about 380nm. As the doping percentage increasing, the defect exciting of ZnO and the luminescence of YAG:Ce3+ get increasing as well. The luminescence of YAG:Ce3+ emitted green due to the electron from excited state of 5d to ground state of 4f. 　　The results of the absorption spectrum show the absorption energy gap of ZnO would get red shift with the increasing doping concentration. Because of the defect density increasing with the doping concentration as well, it results in poor luminescence properties. The n-ZnO:YAG/p-Si devise is made. The characteristic of ohmic contact from the electrode of Ni/Ag alloy on the p-Si substrate. The I-V is with the rectifying behavior and the starting voltage (Vth) is about 5V. According to PL, we can observe that the peak value of YAG:Ce3+ , and it would appear in the purple-white light after excited.

並列關鍵字

ZnO ； YAG phosphors ； spray pyrolysis method ； PL

參考文獻

[62] 許雅瑛，p-MnZnO/n-Si結構光偵測二極體於強磁場下之光電特性的研究，碩士論文，國立台北科技大學光電工程系，2009。

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摻雜YAG螢光粉之奈米結構氧化鋅的光電特性研究

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