Dewetting Patterns of Liquid Gallium on Solid Indium Film

Harnessing liquid metal behavior at solid interfaces opens pathways for functional material fabrication and soft-matter device integration. Leveraging the distinct wettability of liquid gallium (Ga) on solid indium (In) and silicon substrates, we propose a facile dewetting-based method for realizing the self-assembly of interfacial patterns. Nonequilibrium eutectic-type Ga liquid and In film systems are constructed, and the self-assembled behaviors of the "feather" and "cell" patterns at the interface under the effect of surface tension-driven dewetting and oxide film-induced wetting have been disclosed. Ga globules diffuse and spread across the surface and grain boundaries of In films. When the In metal film (100 nm thick) completely alloys with the Ga, the already spread Ga liquid phase destabilizes and dewets. Under the coupling of surface tension, oxidative wetting effects, and the pinning effect of the three-phase contact line, "feather" patterns self-assemble at the dewetting front of Ga globules. Conversely, when Ga globules are deposited on a thicker In metal film (500 nm thick), the In film does not undergo complete alloying with Ga, preventing large-scale dewetting. The localized alloying of In and the subsequent dewetting of Ga lead to mechanical instability of the oxide film, resulting in wrinkles and the appearance of "cell" patterns. We further conclude the patterning mechanisms of different types of liquid metal and solid metal systems. These results provide fundamental insight into liquid-solid metal interfacial dynamics and allow for tunable pattern formation.