Silicon Spike Anti-Reflection Surface for Sun Sensor Ghost Image Reduction
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Solution Overview
Problem
Existing anti-reflection surfaces for sun sensors are either expensive to fabricate or easily damaged, limiting their effectiveness in applications like planetary surface exploration missions where accurate sun angle determination is critical.
Innovation Solution
A device with a silicon substrate featuring high-aspect ratio silicon spikes and nano-tips coated with a metallic layer, specifically a Chromium/Gold layer, is used to form an anti-reflection surface that reduces reflection by absorbing light and preventing ghost images in sun sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a porous silicon surface is used as an antireflection surface, then antireflective performance is improved, but the structure is easily damaged
Solution Approach 1:
The invention changes the geometric parameters of the antireflection structure by using high-aspect-ratio silicon spikes with carefully controlled dimensions (spike height 1-10 μm, base diameter 0.1-1 μm, tip radius <100 nm). These specific parameter values optimize both the antireflective performance and mechanical strength, resolving the contradiction between low reflectance and structural durability
Solution Approach 2:
The invention creates a composite structure combining silicon spikes with a metallic coating layer (such as chromium or gold). This composite material approach provides both the antireflective properties from the spike geometry and the mechanical strength from the metal coating, simultaneously achieving low reflectance and high durability
2Object-affected harmful factors
If a sub-wavelength structure with surface grating period smaller than light wavelength is used for an antireflection surface, then antireflective performance is improved, but fabrication cost increases
Solution Approach 1:
The invention uses self-organized nanoscale structures with characteristic dimensions in the sub-wavelength range (tip radius <100 nm, base diameter 0.1-1 μm) that provide excellent antireflective performance. These structures can be fabricated using standard semiconductor processing techniques like reactive ion etching and chemical vapor deposition, avoiding the need for expensive nanolithography while achieving the required sub-wavelength scale
Solution Approach 2:
The invention employs self-organized growth mechanisms during the silicon spike formation process, where the structure automatically organizes itself at the nanoscale without requiring precise lithographic patterning. This self-organization capability enables cost-effective fabrication of sub-wavelength structures using conventional semiconductor manufacturing equipment
3Object-affected harmful factors
If high-aspect ratio silicon spikes are used to form the anti-reflection surface, then reflectance is reduced, but manufacturing complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct, manageable steps: forming a sacrificial mask layer, performing reactive ion etching to create the spike structures, and applying metallic coating. Each step uses standard semiconductor processing equipment and techniques, making the complex high-aspect-ratio structure fabrication manageable and reproducible
Solution Approach 2:
The invention uses a sacrificial mask layer (such as photoresist or silicon oxide) as an intermediary during fabrication. This intermediary structure guides the formation of the silicon spikes and is removed after the desired high-aspect-ratio structures are created, enabling complex geometry formation through simple etching processes
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 anti-reflection surface achieves a significant reduction in reflectance, with specular reflectance as low as 0.09% at a target wavelength, compared to 35% for bare silicon, effectively minimizing ghost images and enhancing the accuracy of sun sensors without the need for expensive nanolithography.
Implementation Method 1
light reflected by the sensor apparatus toward the first side of the silicon substrate is absorbed by the silicon spikes and is thereby prevented from being reflected toward the sensor apparatus
Implementation Method 2
A first metallic layer is formed on the silicon spikes, thereby forming an anti-reflection surface
Data Source
AI summary
Described is a device having an anti-reflection surface. The device comprises a silicon substrate with a plurality of silicon spikes formed on the substrate. A first metallic layer is formed on the silicon spikes to form the anti-reflection surface. The device further includes an aperture that extends through the substrate. A second metallic layer is formed on the substrate. The second metallic layer includes a hole that is aligned with the aperture. A spacer is attached with the silicon substrate to provide a gap between an attached sensor apparatus. Therefore, operating as a Micro-sun sensor, light entering the hole passes through the aperture to be sensed by the sensor apparatus. Additionally, light reflected by the sensor apparatus toward the first side of the silicon substrate is absorbed by the first metallic layer and silicon spikes and is thereby prevented from being reflected back toward the sensor apparatus.