In the case of gold base plate in MIM, the transmittance was about 40%. If the thickness of gold was less than 5 nm, an island structure will be formed and the film will not be uniform. This is the reason that 5 nm Au cannot serve as the base plate in MIM. However, on a substrate such as mica, a flat curtain can be obtained at the atomic level of gold , so it is thought that further thinning of gold can be realized. In the case of gold, it is necessary to place about 4 nm of Cr as an adhesive layer for each layer of dielectric, which cause large losses in light transmission. In addition, the experimental requirement for gold to have a film thickness of 10 nm will also lead to reduction in transmittance of visible light.