Transparent Semiconductor Window Coating for EMI Shielding
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Solution Overview
Problem
Conventional electrically conductive optical coatings for broadband optics face challenges in achieving broadband optical transmittance while maintaining electrical conductivity and minimizing light scattering and EMI interference.
Innovation Solution
A method of coating an optical substrate with a semiconductor coating that is undoped initially, followed by selective doping to form a pattern, which is then activated for conductivity, and optionally applying a protective and anti-reflection coating, without etching or polishing, to create a window with matched refractive indices and reduced scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous transparent conductive coating is used, then electrical conductivity and EMI attenuation are improved, but optical transmittance decreases due to plasma reflectance and free-carrier absorption
Solution Approach 1:
The continuous conductive coating is segmented into a grid pattern of conductive lines separated by transparent spaces. This segmentation allows light to pass through the gaps between lines while maintaining EMI shielding through the conductive paths, resolving the contradiction between conductivity and transmittance.
Solution Approach 2:
Different regions of the window have different properties: the grid lines provide electrical conductivity and EMI shielding, while the spaces between lines maintain optical transparency. This local differentiation allows simultaneous achievement of both EMI shielding and optical transmittance.
2Adaptability or versatility
If a grid of fine metal lines is applied for broadband applications, then optical transmittance over broad wavelength range is enabled, but optical transmittance is limited by obscuration and scattering
Solution Approach 1:
The invention changes the material parameter from traditional metal to transparent conductive semiconductor material for the grid lines. This material parameter change reduces optical absorption and scattering while maintaining electrical conductivity, enabling improved broadband transmittance compared to metal grids.
Solution Approach 2:
The window combines transparent semiconductor material with conductive properties to create a composite structure that exhibits both optical transparency and electrical conductivity, resolving the contradiction between broadband transmittance and scattering/obscuration from conventional metal grids.
3Reliability
If doping is increased to increase electrical conductivity and EMI attenuation, then electrical conductivity is improved, but optical transmittance decreases
Solution Approach 1:
Instead of uniformly doping the entire coating to achieve conductivity, the invention applies doping only to the grid line regions where conductivity is needed. This partial doping action achieves the required electrical conductivity while minimizing the impact on overall optical transmittance, as the dopant is concentrated only where necessary for EMI shielding.
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 a window with superior broadband optical transmittance, effective EMI shielding, and minimal light scattering, enhancing the performance of electro-optic systems.
Implementation Method 1
applying a photoresist over the semiconductor coating. The photoresist can be selectively exposed and developed in the pattern
Implementation Method 2
Activating the doped semiconductor can include at least one of heat-treating or laser annealing the doped semiconductor
Implementation Method 3
Activating the doped semiconductor can include at least one of heat-treating or laser annealing the doped semiconductor
Implementation Method 4
Doping the semiconductor coating to form a pattern can include at least one of applying dopant by ion implantation
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.