Uni-directional liquid spreading realized by laser-based surface structuring

In our work, we suggest a simple one-step method for the fabrication of slanted surface structures. Spikes - self-organized, quasi-periodical arrays of high aspect ratio micro structures - can be fabricated e.g. by laser irradiation of silicon (Si) surfaces in a reactive gas atmosphere (e.g. SF₆). Moreover, spikes generation was reported on a wide range of materials, including semiconductors and metals. The geometrical parameters of spikes (their dimensions and density) are mainly controlled by changing the incident laser fluence (laser pulse energy per unit area). Already in the first reports dealing with the generation of spikes, it was established that the spikes always point in opposite direction of the incident laser beam. Therefore, it is possible to generate slanted spikes by mounting samples at different angles to the incident laser beam. We use this method to fabricate slanted spike microstructures.