Spontaneous formation of ordered patterns in Al films deposited on silicone oil surfaces

We report the spontaneous formation of large spatial ordered patterns in a continuous aluminum (Al) film system deposited on silicone oil surfaces by a thermal evaporation method. The growth mechanism of the ordered patterns can be traced to a three-stage process, the first of which involves nucleation and growth of strips with a characteristic domain structure in the films. In the subsequent stage, triangle-shaped domains with different sizes appear in the strips. Then the domains grow and finally form the ordered and band-shaped patterns. The experiment shows that the ordered patterns result from the spontaneous ordered organization of the Al atoms and atomic clusters driven by the internal stress in this nearly free sustained film system.