Nanoroughness induced anti-reflection and haze effects in opaque systems

TL;DR

This paper proposes a nanoscale surface modification method to achieve anti-reflection and haze reduction in opaque high-refractive-index materials, supported by theoretical analysis and experimental validation.

Contribution

It introduces a novel approach based on boundary condition theory to induce anti-reflection through nanoroughness, a concept not previously demonstrated.

Findings

Nanoroughness reduces specular reflection in opaque materials.

Experimental validation on nano-roughened Si films supports theoretical predictions.

Haze effects are polarization-dependent, with minimal haze at nanoscale.

Abstract

How to make a material anti-reflective without changing its high refraction index? Achieving anti-reflection in high-refractive-index materials poses challenges due to their high reflectivity (Fresnel equations). Based on theory with new boundary conditions, we propose modifying surface properties on a nanoscale to tackle this. Our study on weakly rough opaque surfaces reveals significant changes in specular and diffuse scattering, predicting anti-reflection where roughness matches light penetration depth for the first time. Experimental validation on nano-roughened Si films (at wavelengths 300-400 nm) supports our findings. We also analyze angular and polarization dependences of nanoroughness-induced haze, showing predominant p-polarization and minimal haze at nanoscale, yet impactful specular reflection reduction.