Growth mechanism and ordered structures of iron films sputter-deposited on silicone oil surfaces

Abstract

A series of iron films has been successfully fabricated by deposition on silicone oil surfaces using the DC-magnetron sputtering method, and the growth mechanism and ordered surface morphologies have been systematically studied. It is found that the growth mechanism of the iron films is similar to that of nonmagnetic films on liquid substrates,in accordance with a two-stage growth model. Large disk-shaped patterns (disks) are observed in the continuous films and their growth behaviors are mainly related to the sputtering power, deposition time and growth duration in vacuum. The experiment indicates that the disks may result from the spontaneous, free organization and gathering of the iron atoms and atomic clusters driven by the internal stress. If the sputtering power and deposition time are comparatively large, wavy buckles with a nearly uniform wavelength of about 10 μm are observed in the continuous films, generally aligning parallel to the boundaries of the disks. Further analysis shows that the top surface of the silicone oil is modified to form a soft polymer layer during deposition. Subsequent cooling of the system creates compressive stress in the iron film, which is relieved by buckling to form the wavy structures.