Si基CeO2/Tb4O7超晶格薄膜发光特性的研究

利用电子束蒸发技术在P型硅衬底上沉积了CeO2 /Tb4 O7超品格样品,将样品置于弱还原气氛中高温退火后,观察到薄膜样品在488,544,588以及623 nm左右出现Tb3+的四个典型发光峰.结合激发光谱、吸收光谱以及XRD分析表明,CeO2薄膜在高温下失氧,发生Ce4+→Ce3+转变,Ce3+吸收紫外光后,Ce3+与Tb3+发生能量传递,产生发光.通过改变Tb4 O7薄膜厚度,研究了Tb4 O7层厚对超晶格发光的影响,结果显示在Tb4 O7层厚为0.5nm时,发光强度最大;Tb4 O7层厚大于0.5nm时,由于Tb3+间的能量传递,产生浓度猝灭.同时,对超晶格样品在900～1 200℃之间进行了不同温度、不同时间的退火,结果显示在1 200℃下进行2h的退火,薄膜发光强度达到最大.研究认为,Ce3+的浓度、氧空位缺陷以及Ce3+与Tb3+间距的变化是导致这一结果的主要原因.

A study of photoluminescence properties of Si-based CeO2/Tb4O7 superlattices

CeO2/Tb4O7 superlattices were deposited on P type Si wafers by e-beam evaporation technology. Four typical photoluminescence peaks of Tb3+ ions which located around 488, 544, 588 and 623 nm were obtained after the superlattices annealing in weak reducing atmosphere at high temperature. It was indicated that CeO2 films transferred to amorphous state as the valence transition of Ce4+ --> Ce3+ which was induced by thermal annealing, the energy transfer occurred between Ce3+ ions and Tb3+ ions, and the Tb3+ ions emition could be detected after obtaining the energy from Ce3+ ions. A study about the effect of Tb4O7 thickness on the superlattices photoluminescence showed that the maximum PL intensity as thickness of Tb4 O7 films were about 0.5 nm, the concentration quenching might occur because of the energy transfer among the Tb3+ ions. The annealing conditions research demonstrated that the maximum PL intensity could be obtained as the superlattices annealed at 1 200 degrees C for 2 hour. Further investigation inferred that the concentration of Ce3+ ions, Oxygen vacancy defects and the distance between Ce3+ ions and Tb3+ ions play an important role in the annealing process.