Structure Evolution and Formation Mechanism of Wrinkled Fe Films on Liquid Surfaces

A characteristic wrinkled Fe film system has been prepared on silicone oil surfaces by a direct current magnetron sputtering method. The experiment shows that the Fe film is under a large compressive stress induced by the thermal contraction during deposition, which is relieved by the formation of wrinkling patterns. It is found that the wrinkling patterns, such as straight strips and herringbones, are formed in networked domains. The straight strips are perpendicular to the domain edges and the herringbones are located in the center of the domains. The morphologies of the wrinkled patterns are characterized by the optical microscopy and atomic force microscopy. It is found that the average length d of the domains remains nearly unchanged and the wavelength λ of the wrinkling patterns increases linearly with the film thickness h, which obeys an equation λ = 14h + 1440. The amplitude z of the herringbones increases firstly with the film thickness h for h ≤ 450 nm and decreases quickly for h > 450 nm. The characteristic, structure evolution and formation mechanisms of the wrinkled patterns have been described and discussed in detail.