近红外波段导电氧化物等离子体材料的光学性能研究

It is well known noble-metal exhibits interesting surface plasmon resonance effects in the visible range. However, due to the large loss in the metal, it is difficult to be applied in the near infrared wavelength range. Thus, the searching for the better, low-loss plasmon materials in the near infrared is urgently required. In this project we will study the optical properties of transparent conductive oxide films in the near infrared and discuss their plamon properties. We will studied the possibility of Nb or Ta-doped TiO2 films as the plasmon materials in the optical frequency range. The samples with differernt nano-structure will be fabricated. The effects of growth parameter, annealing on the microstructur of the samples will be investigated. Also, the nonlinear optical properties of the samples will be studied by z-scan method using femtosecond laser excitation under different wavelength, espically in the infrared wavelength range. The inherent relationship between the optical properties and the electronic, microstructure in the samples will be discussed. Based on the theoretical studies and experimental results, we will try to find the possibility of how to control the plasmon peroperties of the sample in the near infrared. The above studied and results will provide a deeper understanding the optical properties of conductive oxide films, which can be apllied in many fields, such as optoelectronics, information communication in the future.

贵金属在可见光范围内是很好的等离子体材料，但由于其存在的损耗很大，无法应用到近红外波段，因此寻找可替代的、低损耗的近红外波段的等离子体材料成为科学家们关注的热点。本项目将开展近红外波段导电氧化物等离子体材料光学性能的研究工作，通过脉冲激光沉积、磁控溅射并结合刻蚀技术制备不同纳米结构的导电氧化物材料，重点探索以TiO2 为基、掺Nb 或Ta 作为等离子体材料的波长适用范围。研究生长条件、退火处理、刻蚀条件、对材料微结构的影响，利用飞秒激光(50fs/1KHz/2mJ，波长在400 纳米-10 微米连续可调)研究其近红外波段的非线性光学特性，讨论其光学性能与材料电子特性、微结构的内在关系，结合理论研究和实验结果，探索其光学性能的可调性(如等离子体效应的波长调控)，为该体系材料在未来光电子、信息通讯等相关领域的应用提供科学依据。

本项目的主要内容是研究导电氧化物薄膜材料的制备及其光电性质，探索其在近红外波段作为等离子体材料应用的可能性。首先，我们通过脉冲激光沉积技术技术制备了高结晶性的LiNiMnO4氧化物薄膜，其循环特性和大电流放电能力接近国际最好水平，而通过外层Al2O3薄膜的包覆，其充放电的稳定性得到了大大提高。在此基础上，我们探索了掺Na的NiMnO4新型结构的薄膜性能，发现其同样具有较好的稳定性，经过30次循环，容量保持率保持在91%以上，结合x射线衍射、x光电子能谱对薄膜性能的物理机制进行了讨论。其次，我们通过磁控溅射和脉冲激光沉积技术（PLD）外延生长了不同掺杂浓度的Nb（Ta）:TiO2、Al（Ga）:ZnO导电氧化物氧化物薄膜，实现了TiO2薄膜不同相结构的控制生长，，研究了不同生长条件对薄膜结构、结晶性及其光学性能影响。结果发现退火温度可以有效改善薄膜的光学和电学性质，在可见光范围内透过率达到90%，其电阻率达到10-4Ωcm ，载流子浓度高达1021次方每立方厘米。我们还探索了Nb、Ga共掺TiO2薄膜的生长及其性能，发现溅射功率对薄膜结晶性以及光学、电学性质影响很大。在210W情况下生长的样品，光学透过率高于83%，电阻率接近10-4量级，是良好的透明导电氧化物材料。