Co，Sn共掺ZnO薄膜结构与光致发光的研究

Effects of Co and/or Sn doping on crystal structures and optical properties of ZnO thin films

采用溶胶-凝胶旋涂法在玻璃衬底上制备了Co,Sn掺杂ZnO系列薄膜.通过金相显微镜和X射线衍射(XRD)研究了Co与Sn掺杂对薄膜的表面形貌和微结构的影响.XRD结果表明,所有ZnO薄膜样品都存在(002)择优取向,特别Sn单掺ZnO薄膜的c轴择优取向最为显著,而且晶粒尺寸最大.XPS测试表明样品中Co和Sn的价态分别为2+和4+,证实Co2+,Sn4+进入了ZnO的晶格.室温光致发光谱(PL)显示在所有的样品中都有较强的蓝光双峰发射和较弱的绿光发射,而在纯ZnO及Co掺杂ZnO薄膜样品中还观察到了较强的紫外发光峰.此外,通过Co,Sn掺杂的控制能够调整薄膜的禁带宽度,进而使得蓝光发光峰发生了位移;同时,掺杂还将影响薄膜中氧位错、锌空位和锌填隙缺陷,因此控制掺杂浓度可以调控薄膜的发光特性.最后,还探讨了不同波段光发射的可能机理.

The Co and/or Sn doped ZnO thin films are deposited on the glass substrates by the sol-gel method. The effects of Co and/or Sn doping on surface morphologies and mircrostructures of ZnO films are investigated by metallurgical microscope and X-ray diffraction （XRD）. The XRD results indicate that all the ZnO samples show preferential orientation along the （002） direction, and that the Sn-doped ZnO thin film exhibits the best c-axis orientation and largest grain size. XPS results reveal that Co and Sn elements exist as Co2＋ and Sn4~ , indicating that Co and Sn ions have entered into the ZnO crystal lattices successfully. Strong blue double emission and weak green emission are observed in the PL spectra of all the samples. In addition, the ultraviolet peaks appear in the undoped and the Co-doped ZnO thin films. Our results reveal that the Co and/or Sn doping can tune the band gap, meanwhile, such a doping can also affect oxygen dislocation, zinc oxygen and zinc interstial defect concentrations. Finally, ZnO films are discussed. the possible luminescence mechanisms of Co and/or Sn doped