Periodic patterning of silicon by direct nanosecond laser interference ablation

• Published in: Applied surface science 2011-11, Vol.258 (3), p.1175-1180
• Main Authors: Tavera, T., Pérez, N., Rodríguez, A., Yurrita, P., Olaizola, S.M., Castaño, E.
• Format: Article
• Language: English
• Subjects: Ablation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Interference; Laser ablation; Lasers; Nanocomposites; Nanomaterials; Nanostructure; Nanostructuring; Physics; Reflectivity; Silicon; Solar cells
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.09.062

► Silicon solar grade wafers are processed to decrease their reflectivity. ► Direct ablation by laser interference is used as the structuring technique. ► Three different structures obtained: periodical bumps, nanoripples, microripples. ► Silicon reflectance diminishes probably due to the presence of nanoripples. The production of periodic structures in silicon wafers by four-beam is presented. Because laser interference ablation is a single-step and cost-effective process, there is a great technological interest in the fabrication of these structures for their use as antireflection surfaces. Three different laser fluences are used to modify the silicon surface (0.8Jcm−2, 1.3Jcm−2, 2.0Jcm−2) creating bumps in the rim of the irradiated area. Laser induced periodic surface structures (LIPSS), in particular micro and nano-ripples, are also observed. Measurements of the reflectivity show a decrease in the reflectance for the samples processed with a laser fluence of 2.0Jcm−2, probably caused by the appearance of the nano-ripples in the structured area, while bumps start to deteriorate.