Effect of Carrier Diffusion on the Optical Property in Si–In–Zn–O/Ag/Si–In–Zn–O Optical Media

Abstract

Si–In–Zn–O (SIZO)/Ag/Si–In–Zn–O (SIZO) (totally, SAS) multilayered oxide–metal–oxide (OMO) structure has been fabricated and analyzed. Amorphous oxide semiconductor has been uniquely adopted in this study. Different from a metal–dielectric composite multilayer system, carrier diffusion occurred at the semiconductor–metal interface resulting in a complicated electric field distribution in a semiconductor–metal composite multilayer. This phenomenon causes the distortion of bulk permittivity function, therefore mismatching could be found which is confirmed by epsilon-zero-points of samples with different volume filling fraction. Carrier concentration distribution in a SAS was carefully analyzed by introducing Poisson’s electrostatic equation. Further discussion on the distortion of bulk permittivity function in SAS multilayers has been conducted and, carrier diffusion model was introduced to analyze the redistribution of electric field. Carrier concentration dependency of frequency of transmitted light has been investigated and established with a correction parameter related with the total thickness of the samples. It is expected that this research would not only provide a solution to correct the distorted bulk permittivity function of semiconductor–metal multilayer system, but also reveal a potentially promising method for designing a carrier concentration controllable meta-material, such as low-emissivity coating, or low-loss plasmonic for an optical integrated circuits.