Antireflective hydrophobic si subwavelength structures using thermally dewetted Ni/SiO2 nanomask patterns

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Silicon subwavelength structures (SWSs) offer potential for advanced optical applications.
• Developing broadband antireflective and self-cleaning surfaces is crucial for various technologies.

Purpose of the Study:

• To fabricate disordered silicon (Si) SWSs using inductively coupled plasma (ICP) etching.
• To achieve broadband antireflective and self-cleaning properties on Si substrates.
• To investigate the optical characteristics and surface hydrophobicity of the fabricated Si SWSs.

Main Methods:

• Fabrication of Si SWSs via ICP etching in SiCl4 gas using Ni/SiO2 nanopatterns.
• Thermal dewetting of Ni films to form Ni nanoparticles for etch masks.
• Experimental investigation of antireflection properties and theoretical analysis using rigorous coupled-wave analysis (RCWA).
• Measurement of water contact angle to assess surface hydrophobicity.

Main Results:

• Truncated cone-shaped Si SWSs with an average height of 790 nm were fabricated.
• A low average reflectance of approximately 5% was achieved across the 450-1050 nm wavelength range.
• A hydrophobic surface with a water contact angle of 110 degrees was obtained.
• Experimental reflectance data showed good agreement with RCWA calculations.

Conclusions:

• Disordered Si SWSs fabricated by ICP etching provide effective broadband antireflection.
• The fabricated surfaces exhibit desirable self-cleaning properties due to their hydrophobicity.
• The study demonstrates a viable method for creating advanced optical and functional surfaces on silicon.