2024/03/21 by Katkus, Tomas, Ng, Soon Hock, Mu, Haoran +14
#Applied Physics (physics.app-ph) #FOS: Physical sciences #Optics (physics.optics)
paper · doi:10.48550/arxiv.2403.14237
Large surface area applications such as high-efficiency > 26% solar cells require surface patterning with 1-10 micrometers periodic patterns at high fidelity over 1-10 cm2 areas (before up scaling to 1 m2) to perform at, or exceed, the Lambertian (ray optics) limit of light trapping. Here we show a pathway to high-resolution sub-1 micrometer etch mask patterning by ablation using direct femtosecond laser writing performed at room conditions (without the need for a vacuum-based lithography approach). A Bessel beam was used to alleviate the required high surface tracking tolerance for ablation of 0.3-0.8 micrometer diameter holes in ~40 nm alumina Al2O3-mask at high writing speed, 7.5 cm/s; a patterning rate 1 cm2 per 20 min. The plasma etching protocol was optimised for a zero-mesa formation of photonic crystal (PhC) trapping structures and smooth surfaces at the nanoscale level. Scaling up in area and throughput of the demonstrated approach is outlined.