Hussin Rosniza, Choy Kwang-Leong, Hou Xianghui
Faculty of Engineering, Department of Mechanical Materials and Manufacturing Engineering, University of Nottingham NG7 2RD, United Kingdom.
J Nanosci Nanotechnol. 2011 Sep;11(9):8143-7. doi: 10.1166/jnn.2011.5086.
Bilayer and multilayer thin films are becoming increasingly important in the development of faster, smaller and more efficient electronic and optoelectronic devices. One of the motivations of applying bilayer or multilayer structures is to modify the optical properties of materials. Atomic layer deposition (ALD) is a variant of Chemical Vapour Deposition that can produce uniform and conformal thin films with well controlled nanostructures. In this study, we have demonstrated new findings of the use of ALD fabricated bilayer TiO2/ZnO thin films with enhanced crystallinity and optical properties. TiO2 films have been deposited at 300 degrees C for 1000 (51 nm in thickness) or 3000 (161 nm in thickness) deposition cycles onto glass and Si substrates. ZnO films are subsequently deposited on the TiO2 layers at 280 degrees C for 500 deposition cycles (55 nm). The crystallinity and optical properties of the TiO2/ZnO thin films have been analysed by X-ray diffraction, photoluminescence, UV-Vis spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. XRD diffraction pattern confirmed the presence of ZnO with wutrtize crystal structure and TiO2 with anatase structure. It shows that the crystallinity of the TiO2 films has been improved with the deposition of ZnO. The intensity of UV luminescence has increased by almost 30% for TiO2/ZnO bilayer as compared to the single layer TiO2. The possible mechanism for the enhancement of the optical properties of bilayer TiO2/ZnO thin films will be discussed.
双层和多层薄膜在更快、更小且更高效的电子和光电器件的发展中变得越来越重要。应用双层或多层结构的动机之一是改变材料的光学性质。原子层沉积（ALD）是化学气相沉积的一种变体，它可以制备具有良好控制的纳米结构的均匀且保形的薄膜。在本研究中，我们展示了使用ALD制备的具有增强结晶度和光学性质的双层TiO2/ZnO薄膜的新发现。TiO2薄膜已在300摄氏度下沉积1000次（厚度为51纳米）或3000次（厚度为161纳米）循环，沉积在玻璃和硅衬底上。随后，ZnO薄膜在280摄氏度下在TiO2层上沉积500次循环（55纳米）。通过X射线衍射、光致发光、紫外-可见光谱、原子力显微镜和扫描电子显微镜对TiO2/ZnO薄膜的结晶度和光学性质进行了分析。XRD衍射图谱证实了具有纤锌矿晶体结构的ZnO和具有锐钛矿结构的TiO2的存在。结果表明，随着ZnO的沉积，TiO2薄膜的结晶度得到了改善。与单层TiO2相比，TiO2/ZnO双层的紫外发光强度增加了近30%。将讨论双层TiO2/ZnO薄膜光学性质增强的可能机制。
