Nanosecond laser induced periodic silicon microstructures for broadband antireflective applications

Abstract

Laser-driven micro/nano-texturing is a remarkably efficient and cost-effective technique, having diverse applicability in the realm of photonics, optoelectronics, and photovoltaics. Here, we demonstrate the high-intensity nanosecond laser-matter interactions for periodic micro/nanostructures on silicon, exclusively to emphasize the effects of laser parameters for large-scale integration. A wide range of periodic structure rapid fabrication over a wafer level is systematically studied for optimised parameters using nanosecond laser pulses (1064 nm, 50 ns) at different pulse repetition rates ranging from 10 to 40 kHz. A comprehensive understanding based on physical, structural, and optical studies reveals a strong correlation between the formation of nano/microstructure morphology and the laser parameters. The laser-matter interactions result in trench-like periodic patterns, formation of nanostructure agglomerations as light-trap-centres on the silicon surface. Such nano/micro periodic structures provide a dominant reduction in reflection losses of up to 80 % over a broad UV-NIR spectral region. The studies further demonstrate that the periodic structural patterns could also be potentially utilised for large-scale optical diffraction applications. In addition, the extra layer coating of Silicon Nitride (Si3N4) on the textured silicon further reduces the reflection losses, which is an added advantage of integrated silicon technology. The present work could open a commercial pathway for the rapid fabrication of nanosecond laser-based nanotexturing and periodic grating structures, enabling significantly reduced reflection and improved light trapping in large-scale Silicon-based applications due to its speed, repeatability, and high precision.