Fabrication of durable superhydrophilic silicon surfaces using nanosecond laser pulses
Nancy Verma, K. K. Anoop, Priya Dominic, Reji Philip
Abstract
In this work, we report the fabrication and characterization of large area micro-/nano-textured silicon surfaces using laser pulses of nanoseconds duration. An area of 6×6mm2 has been textured by the parallel line scanning method to create hierarchical structures, consisting of microscale channels and self-organized surface nano-capillaries decorated with randomly distributed silicon nanoparticles. The combination of micro-channels and nano-capillaries results in a superhydrophilic silicon surface, with the contact angle reduced substantially from about 80° to nearly 5°. In contrast to most of the reports given in the literature, the superhydrophilicity of the surface remains stable without a shift to hydrophobicity, even after exposure to the atmosphere for about three months. Thus, long-lasting and durable superhydrophilic silicon has been obtained by using maskless, compact, and cost-effective nanosecond laser writing, without the need to employ any chemical post-processing. Potential applications of these surfaces include heat exchangers, biosensors, cell adhesives, and self-cleaning solar cells.