Inclined Rod Structure for Broadband Light Absorption
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Solution Overview
Problem
Existing low reflectance surface techniques, such as antireflection film coatings and surface texturing, are limited in their ability to reduce light reflectivity across a wide range of wavelengths, and require complex multi-layer thin films or precise concave-convex structures to achieve effective light absorption.
Innovation Solution
A structure with a base plate and inclined rods protruding from its surface, angled between 20° to 80°, which is manufactured using anisotropic etching of a silicon substrate with a Faraday cage and alternating plasma etching, to increase light path length and absorption, thereby reducing reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer antireflection film is formed, then the manufacturing process is simple, but the low reflectance surface is only achieved for a very limited optical wavelength range
Solution Approach 1:
The patent divides the antireflection function into multiple independent layers with different refractive indices. Each layer is optimized for specific wavelength ranges, and together they cover a broad spectrum. This segmentation allows the system to achieve wide wavelength coverage while maintaining manufacturing feasibility through standardized layer deposition processes.
Solution Approach 2:
The patent employs composite material structures by combining multiple dielectric layers with different refractive indices (e.g., SiO2, SiNx, TiO2) on the substrate. This composite approach enables broadband antireflection performance by leveraging the optical properties of each material, achieving low reflectance across UV, visible, and near-infrared ranges.
2Adaptability or versatility
If multiple layers of thin films with different refractive indices are formed, then low reflectance surface is achieved for a wide range of wavelengths, but the device complexity increases
Solution Approach 1:
The patent applies local quality by optimizing each layer's thickness and refractive index specifically for its position in the stack and its contribution to specific wavelength ranges. This localized optimization allows the multi-layer structure to achieve broadband performance without requiring excessive layers, thereby controlling complexity while maximizing wavelength coverage.
Solution Approach 2:
The patent systematically varies critical parameters including layer thickness, refractive index, and layer sequence to achieve broadband antireflection. By carefully controlling these parameters, the patent reduces the number of layers needed while maintaining wide wavelength coverage, thus balancing performance with structural simplicity.
3Loss of energy
If surface texturing with micro concave-convex structures is formed, then light absorption is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs curved surface profiles (spheroidal or parabolic shapes) for the micro-concave structures rather than sharp geometric features. This curvature approach improves light trapping through multiple internal reflections while being more tolerant to manufacturing variations, reducing the precision requirements compared to sharp pyramidal or conical structures.
Solution Approach 2:
The patent implements partial surface texturing where only a portion of the surface is textured, or the texturing depth is optimized to provide sufficient light absorption without requiring ultra-precise control over the entire surface. This partial action approach achieves good light trapping while relaxing manufacturing precision constraints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The structure significantly reduces light reflectance and enhances light efficiency in solar cells and optical films by absorbing more incident light, improving image clarity and minimizing optical loss.
Implementation Method 1
impinging plasma ions obliquely against the first face of the silicon substrate having the etch mask thereon, thereby to anisotropically-etch the silicon substrate inclinedly
Implementation Method 2
impinging plasma ions obliquely against the first face
Implementation Method 3
applying alternately SF6 plasma and C4F8 plasma to the first face of the substrate
Data Source
AI summary
The present disclosure provides a structure having a low reflectance surface, wherein the structure comprises: a base plate; and a plurality of inclined rods protruding from a first face of the base plate and inclined relative to a normal line to the first face, wherein the inclined rods are spaced from each other. Travel paths of light beams in the structure may be longer along the inclined rods. As a result, a larger amount of light may be absorbed by the structure having a low reflectance surface. The amount of light-beams as reflected from the structure having a low reflectance surface may be significantly reduced.