Fe掺杂对溶胶凝胶法制备的ZnO: Ni薄膜结构及发光特性的影响

采用溶胶凝胶法在玻璃基片上制备了ZnO及Ni, Fe共掺杂的Zn_0.95-xNi_0.05Fe_xO (x=0, 0.005, 0.01, 0.03, 0.05) 薄膜. 通过扫描电镜(SEM) 和X射线衍射(XRD) 研究了薄膜样品的表面形貌和晶体结构. 结果表明所有样品都具有(002) 择优取向, Fe掺杂导致ZnO: Ni薄膜的晶体质量变差, 晶粒尺寸减小, 但适当的Fe掺杂有利于获得致密、 均匀的薄膜. XPS测试结果表明样品中Ni离子的价态为+2价, Fe离子的价态为+2价和+3价.室温光致发光(PL) 测量表明, 所有样品均观察到较强的紫外发光峰, 蓝光双峰和绿光发光峰. ZnO: Ni薄膜的发光强度可以通过Fe掺杂进行有效调节. 进而我们讨论了Ni, Fe共掺杂ZnO样品的发光机理.

Effects of Fe doping on the crystal structures and photoluminescences of ZnO: Ni thin films prepared by sol-gel method

Zn_0.95-xNi_0.05Fe_xO (x=0, 0.005, 0.01, 0.03, 0.05) thin films are fabricated on the glass substrates by the sol-gel method. The surface morphologies and crystal structures of the films are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal that preferential orientations are all along the (002) direction in all films. the qualities of ZnO: Ni films for low or high Fe concentration become worse, the crystal grain sizes of ZnO: Ni film are reduced, but moderate Fe doping seems to improve the film quality. XPS results reveal that Ni elements exist as Ni²⁺, and Fe elements exist as Fe²⁺ and Fe³⁺. Strong ultraviolet emission peaks, blue double emission peaks and green emission peaks are observed in the photoluminescence spectra of all samples at room temperature. It is found that the PL intensities of (Ni, Fe) co-doped ZnO films could be well modulated by Fe doping. In combination with other reports, we think that the ultraviolet emission peaks are due to exciton recombination; while the blue double peaks are caused by transition of electrons from the zinc interstitial to the top of the valence band or from the oxygen vacancy to the zinc vacancy. However, the green peak is highly dependent on oxygen vacancy and zinc vacancy formed by doping.