WETTABILITY STUDIES ON FEMTOSECOND-¬LASER-TEXTURED N-TYPE SILICON SURFACES

Srikanth Vipparla; Samuel G.L.; Dongbin Wei

doi:10.17222/mit.2023.838

Srikanth Vipparla Indian Institute of Technology Madras, Chennai, India
Samuel G.L. Indian Institute of Technology Madras, Chennai, India
Dongbin Wei University of Technology Sydney, Australia

DOI: https://doi.org/10.17222/mit.2023.838

Keywords: wettability, texturing, femtosecond laser, hydrophobic, hydrophilic, silicon

Abstract

This present study examines the wetting behavior of N-type silicon surfaces that have been textured using a femtosecond laser. By employing three different patterns, i.e., square pillars, micro dimples, and circumferential grooves, and manipulating key femtosecond laser parameters such as laser power (ranging from 8 W to 12 W) and repetitions (ranging from 40 to 60), the wettability properties of the silicon surfaces are modified. The wettability properties of the surface were evaluated by measuring the contact angle by the sessile-drop method using distilled deionized water as a testing liquid. The textured surfaces displayed various wettability characteristics, varying from hydrophilic to hydrophobic. The hydrophobic behavior was observed on surfaces with a peak laser power of 12 W, 60 repetitions, and the lowest pitch of 160 µm. For the square pillar and micro-dimple textures, contact angles of 146° and 120°, respectively, were measured. Conversely, the circumferential grooves exhibited hydrophilic behavior with a contact angle of 20°. These results were achieved at laser powers of 10 W and 8 W, higher pitch values, and increased repetitions. The contact angle decreased with an increase in pitch and a decrease in repetitions and laser power. Based on the experimental findings, it can be concluded that the wettability of silicon surfaces can be controlled for specific applications using a single-step laser ablation technique. The desired wettability characteristics can be achieved by carefully adjusting the key femtosecond-laser parameters and geometrical features.

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