Research On Photoelectric Properties Of The Metal/Dielectric Films

The metal film is an important part of the optical film. With the development of the material science, vacuum technique along with the thin film industry, the metal film has been widely used in the photoelectric thin film devices field. However, the optical constants of the ultra-thin metal film and the continuous metal film vary widely and the optical constants of the metal film are not easy to obtain. Therefore the optical constants of the metal film are substituted by the bulk metal, causing the unconformity in theoretical design and manufacturing characteristics of the metal/dielectric film. The research purpose of this article is to solving the unconformity in theoretical design and manufacturing characteristics of the metal/dielectric film.Based on the Maxwell's equations, we analyzed the factors that affected the optical constants n,k of the ultra-thin metal film. The theoretical basis that the thickness has an effect on the optical constants of the metal film is obtained. The size effect of the metal film conductivityσhas been analyzed and verified by the experiment. With the methods of resistance thermal evaporation and electron beam heating we prepared different thickness of Cu film, Cr film and Ag film. These films were detected by ellipsometry and simulated by Drude model. The law that the optical constant n, k of the three films change with the wavelengthλhas gained. The optical constants between ultra-thin metal films and bulk metal vary widely and with the increase of the film thickness the results of n, k are close to bulk metal's. The influence law that film thickness has an effect on the transmission spectrum of the metal film is obtained. Through the analysis of the effect that film thickness has on the absorption, dispersion and other optical characteristics of the metal film, we found that the in the visible band the continuous metal film has a high absorption of the long-wave and compared with the dielectric thin films the average dispersion rate is higher in 10/nm～102/nm orders of magnitude. On the basis of the optical constants n,k of the metal film, we adopted the metal/dielectric film design theory and designed the metal/dielectric antireflective films and metal/dielectric transparent conductive films G/0.5ZrO2/0.5ZnS/0.003Ag/0.5ZnS/0.7SiO2/Air that can satisfied the technical indexes. The experimental preparation and sample testing show that in the wavelength of 450nm～700nm. compared with the manufacturing characteristics of the metal/dielectric antireflective films and metal/dielectric transparent conductive films and their theoretical design the average reflectivity difference is 1%, the average transmittance difference is 2%. Therefore, the photoelectric theoretical properties of the metal/dielectric films coincide with their manufacturing characteristics.