ZnO:Eu³⁺薄膜的光致发光和拉曼散射特性的研究

Photoluminescence and Raman Scattering Properties of ZnO:Eu³⁺ Thin Films

摘要:

Abstract: ZnO:Eu³⁺薄膜具有来自Eu³⁺的5DO→7F2跃迁产生的强而尖锐的红色特征峰，非常适合作为光电器件的发光材料。本文首先利用直流磁控溅射在普通载玻片上制备ZnO种子层，然后采用水热法在ZnO种子层上成功制备了ZnO:Eu³⁺薄膜，最后利用X射线衍射仪、光致发光(PL)光谱仪以及拉曼光谱仪对样品进行表征。XRD分析结果表明：ZnO:Eu³⁺薄膜具有六角纤锌矿结构，且沿(002)C轴择优取向生长，另外没有其它衍射峰的出现，掺杂后薄膜的结晶度降低。PL谱测量结果显示，在325 nm波长激发下，强的本征ZnO特征峰几乎完全被抑制，在615 nm附近呈现出Eu³⁺强而尖锐的红色特征峰，所以Eu³⁺成功取代Zn²⁺进入ZnO晶格。另外不同的掺杂比例，ZnO:Eu³⁺薄膜的主峰位置略微有一些偏移。通过掺杂前后的拉曼光谱对比分析发现掺杂后Eu³⁺取代Zn²⁺与O²⁻成键或者与Zn²⁺成键而产生新的拉曼峰。 ZnO:Eu³⁺ film shows a strong and sharp red character peak from the 5DO→7F2 transitions in Eu³⁺ ions, which would be very fit for luminescent material of photoelectric device. A ZnO seed layer is first prepared on a glass substrate by CS-300 DC magnetron sputtering device, and then Eu³⁺-doped ZnO thin films are assembled on the ZnO seed layer using a simple hydrothermal method. X-ray diffraction (XRD) spectrum, Photoluminescence (PL) spectrum and Raman scattering spectrum are used to characterize the ZnO:Eu³⁺ thin films at last. The XRD analysis results show that all ZnO:Eu³⁺ thin films have hexagonal wurtzite structure and along the (002) C-axis preferred orientation growth, beyond that there is no other diffraction peak in the diffraction spectrum, and crystallinity of thin films is decreased after doping with Eu³⁺. The PL spectrum results show that strong intrinsic ZnO characteristic peak was almost completely suppressed with the excitation of 325 nm ultraviolet photons, and a sharp and intense red characteristic peak located at around 615 nm wavelength in the visible region can be observed from the PL spectras of ZnO:Eu³⁺ thin film. So Eu³⁺ successfully substitutes Zn²⁺ in the ZnO lattice. In the different doping ratio, the highest peak of ZnO: Eu³⁺ film have some slight deviation. The Raman spectroscopy comparison of before and after doping analysis reveals that after Eu3+ substitutes Zn²⁺, bonding with O2− or Zn²⁺, new Raman peaks appear in the Raman spectra.