Gong Junbo, Dai Rucheng, Wang Zhongping, Zhang Zengming
Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
The Centre of Physical Experiments, University of Science and Technology of China, Hefei, Anhui 230026, China.
Sci Rep. 2015 Mar 23;5:9279. doi: 10.1038/srep09279.
Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Unlike the bulk optical constants in Palik's database the effective optical constants of ultrathin Ag films are found to strongly depend on the thickness. According to the optical data two branches of thickness dispersion of surface plasmon energy are derived and agreed with theoretical predication. The thickness dispersion of bulk plasmon is also observed. The influence of substrate on surface plasmon is verified for the first time by using ellipsometry. The thickness dependent effective energy loss function is thus obtained based on this optical method for Ag ultrathin films. This method is also applicable to other ultrathin films and can be used to establish an effective optical database for ultrathin films.
通过将椭圆偏振光谱法与透射率法相结合，精确测定了银薄膜的有效光学常数，并同时确定了其有效厚度。与帕利克数据库中的体光学常数不同，发现超薄银薄膜的有效光学常数强烈依赖于厚度。根据光学数据，推导了表面等离子体能量的厚度色散的两个分支，并与理论预测相符。还观察到了体等离子体的厚度色散。首次利用椭圆偏振光谱法验证了衬底对表面等离子体的影响。基于这种光学方法，得到了银超薄膜厚度依赖的有效能量损失函数。该方法也适用于其他超薄膜，可用于建立超薄膜的有效光学数据库。
