Thickness dispersion of surface plasmon of Ag nano-thin films: determination by ellipsometry iterated with transmittance method.

Junbo Gong,Zengming Zhang,Zhongping Wang,Rucheng Dai

doi:10.1038/srep09279

Junbo Gong, Zengming Zhang + Show 2 more

Open Access

https://doi.org/10.1038/srep09279

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Abstract

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.

Highlights

Correspondence and requests for materials should be addressed to Thickness Dispersion of Surface Plasmon of Ag Nano-thin Films: Determination by Ellipsometry Iterated with Transmittance
Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method
In this paper, an ellipsometry iterated with transmittance method is proposed and has been used to determine effective optical constants of nano-thin films

Summary

Method

Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Palik’s optical database in common use is not applicable to ultrathin films in thickness under several tens nanometers considering that it has been proved by many researchers that the optical constants of a film are dependent on thickness when the film is very thin[10,11]. This limitation has caused difficulty to surface analysis area as theorists working on surface electron spectroscopy have found that the simulation results with Palik’s optical data can describe bulk material while have an obvious deviation with experimental results of thin films[12]. There is no any suitable dispersion model for ultrathin metal films

Results

Discussion

Methods