Transparent Semiconductor Coating for EMI Shielding Without Scattering
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Solution Overview
Problem
Conventional electrically conductive optical coatings for broadband optics face challenges in achieving both high EMI shielding and broadband optical transmittance, particularly in the visible and infrared spectra, as increased doping for conductivity reduces optical transmittance and traditional grid patterns cause light scattering.
Innovation Solution
A method involving the deposition of an undoped semiconductor coating over an optical substrate, followed by selective doping to form a pattern, which is then activated for conductivity, using materials like In2O3 or ZnO, and applying a broadband anti-reflection coating to minimize light scattering and maximize transmittance across visible and infrared spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor coating is doped to increase electrical conductivity and EMI attenuation, then electrical conductivity is improved, but optical transmittance decreases
Solution Approach 1:
The patent divides the semiconductor coating into doped and undoped regions. The doped regions provide EMI shielding while the undoped regions maintain optical transmittance. This segmentation allows the coating to simultaneously achieve both EMI attenuation and optical transparency by spatially separating the functional regions.
Solution Approach 2:
The patent applies doping locally to specific regions of the semiconductor coating rather than uniformly throughout. This local quality approach ensures that only the necessary areas have enhanced electrical conductivity for EMI shielding, while other areas remain undoped to preserve broadband optical transmittance.
2Illumination intensity
If a grid of fine metal lines is applied to enable broadband optical transmittance, then optical transmittance is improved, but light scattering and obscuration increase
Solution Approach 1:
The patent replaces the mechanical grid structure of metal lines with a semiconductor-based solution. Instead of using physical metal grid patterns that cause scattering, the patent uses a semiconductor coating with controlled doping that provides EMI shielding through electrical conductivity without the mechanical obstruction and scattering associated with metal grids.
3Reliability
If doping is increased to enhance EMI shielding, then EMI attenuation is improved, but plasma reflectance and free-carrier absorption increase at longer wavelengths
Solution Approach 1:
The patent segments the semiconductor coating into doped and undoped regions to address wavelength-dependent transmittance issues. The doped regions provide EMI attenuation while undoped regions maintain transmittance at longer wavelengths where plasma reflectance and free-carrier absorption would otherwise degrade performance.
Solution Approach 2:
The patent changes the doping parameter spatially within the coating, creating regions with different electrical properties. This parameter change allows optimization of EMI shielding in doped regions while preserving optical transmittance at various wavelengths in undoped regions.
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 solution provides electrically conductive coatings with improved EMI shielding and broadband optical transmittance without the need for etching or polishing, reducing light scattering and maintaining optical clarity across a wide wavelength range.
Implementation Method 1
the semiconductor coating, e.g., an undoped semiconductor coating, has broadband optical transmittance
Implementation Method 2
The doped semiconductor in the pattern is activated for electrical conductivity
Implementation Method 3
The pattern can be configured to provide electromagnetic interference (EMI) shielding to the optical substrate
Implementation Method 4
depositing a broadband anti-reflection coating over the protective coating
Implementation Method 5
reducing light scattering and maintaining optical clarity
Implementation Method 6
Activating the doped semiconductor can include at least one of heat-treating or laser annealing the doped semiconductor
Implementation Method 7
Activating the doped semiconductor can include at least one of heat-treating or laser annealing the doped semiconductor
Data Source
AI summary
A method of coating an optical substrate with a transparent, electrically conductive coating includes depositing a semiconductor coating over a surface of an optical substrate, wherein the semiconductor coating has broadband optical transmittance. A doped semiconductor is applied in a pattern over the semiconductor coating. The doped semiconductor in the pattern is activated for electrical conductivity in the doped semiconductor.