Dielectric properties and the optical energy gap of multilayer films prepared by sputtering were measured. The thickness ratio, , was fixed at 1/3, and monolayer thickness, , was varied from 0.3 to 60 nm. The peak of the maximum charge density, which is the product of the dielectric constant and the breakdown field strength, was observed at . The optical energy gap was constant for , and increased as dropped below 2 nm. The films of are thought to be a composite whose contents vary periodically, and there is no bulk .