Studies on Femtosecond Laser Textured Broadband Anti-reflective Hierarchical a-SiNx:H Thin Films for Photovoltaic Applications
Pariksha Malik, Jitendra Nath Acharyya, Mohd Shanu, Albin Kuriakose, Santanu Ghosh, Pankaj Srivastava, G. Vijaya Prakash
Abstract
Simple ultrafast laser writing for the fabrication of hierarchical silicon nitride (a-SiN x:H) microstructures is demonstrated as an effective antireflection coating. A wide range of Si-rich to N-rich a-SiN x:H thin films, having varied optical band gap (2.32–5.94 eV) and refractive index (2.8–1.7) of wavelength-ordered (∼λ/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-SiN x: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 ∼ 1 cm 2 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.