Studies on Femtosecond Laser Textured Broadband Anti-reflective Hierarchical a-SiNx:H Thin Films for Photovoltaic Applications

Simple ultrafast laser writing for the fabrication of hierarchical silicon nitride (a-SiNx:H) microstructures is demonstrated as an effective antireflection coating. A wide range of Si-rich to N-rich a-SiNx:H thin films, having varied optical band gap (2.32-5.94 eV) and refractive index (2.8-1.7) of wavelength-ordered (similar to lambda/4) thickness, are deposited using the plasma enhanced chemical vapor deposition technique. The high-intensity femtosecond laser (800 nm, 120 fs, 1 kHz) interaction with a-SiNx:H films resulted in diverse nano-/microstructures with systematic width and depth born out of nonlinear light-matter interactions. These experimentally demonstrated the extremely disordered micro-nano structures over a large area of similar to 1 cm2 that exhibit significant light trapping and absorption capabilities over a broad spectral region of 200-1000 nm. The extensive reduction of reflection losses from 30 to 2.8% from pre-to post-laser texturing is a favorable condition for broadband anti-reflective coatings for enhanced light harvesting from prefabricated photovoltaic devices.

Automated summary

In this study, a simple and fast laser writing technique was used to fabricate hierarchical silicon nitride (a-SiNx:H) microstructures for antireflection coating. The a-SiNx:H thin films with a wide range of optical band gap (2.32-5.94 eV) and refractive index (2.8-1.7) were deposited using plasma enhanced chemical vapor deposition. The interaction between high-intensity femtosecond laser and a-SiNx:H films resulted in diverse nano-/microstructures with significant light trapping and absorption capabilities.