GaAs IR Window EMI Shielding via Doped Layer Optimization
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Solution Overview
Problem
Existing methods for manufacturing EMI-shielded IR windows face challenges in achieving transparency over a wide range of IR wavelengths while providing effective EMI shielding without complex and costly processing steps.
Innovation Solution
The method involves manufacturing single crystalline semiconductor windows, such as GaAs and GaP, with a doped layer of the same material applied for EMI shielding. This approach includes accurately modeling the IR transparency and conductivity of the EMI shielding layer to determine optimal layer thickness and dopant concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a doped semiconductor layer is applied to provide EMI shielding, then EMI shielding effectiveness is improved, but infrared transparency deteriorates due to free carrier absorption
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dopant concentration and layer thickness of the semiconductor coating. By optimizing these parameters, the patent achieves a balance where the doped layer provides sufficient EMI shielding while maintaining infrared transparency through minimized free carrier absorption at infrared wavelengths.
Solution Approach 2:
The patent uses composite materials by combining the base semiconductor substrate with a doped semiconductor layer. This composite structure leverages the inherent infrared transparency of the undoped semiconductor while the doped layer provides EMI shielding, creating a multi-functional window material that addresses both requirements simultaneously.
2Reliability
If heavy doping is used to enhance EMI shielding, then electrical conductivity is improved, but infrared absorption increases due to free carrier absorption
Solution Approach 1:
The patent applies parameter changes by optimizing the dopant concentration to a specific range that provides sufficient electrical conductivity for EMI shielding while avoiding excessive doping that would cause strong free carrier absorption in the infrared region. The patent also controls layer thickness as a critical parameter to balance shielding effectiveness with infrared transparency.
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
This method achieves IR transparency over a wide range of wavelengths while providing effective EMI shielding with minimal optical artifacts and loss of transparency, avoiding the need for complex and costly processing steps.
Implementation Method 1
a doped layer of the same material is applied to the slab to shield the slab against electromagnetic radiation
Implementation Method 2
a doped layer of the same material is applied to the slab to shield the slab against electromagnetic radiation
Implementation Method 3
The GaAs window is grown by HVPE
Data Source
AI summary
A method of manufacturing a structurally competent, EMI-shielded IR window includes using a mathematical model that combines the Sotoodeh and Nag models to determine an optimal thickness and dopant concentration of a doped layer of GaAs or GaP. A slab of GaAs or GaP is prepared, and a doped layer of the same material having the optimal thickness and dopant concentration is applied thereto. In embodiments, the doped layer is applied by an HVPE method such as LP-HVPE, which can also provide enhanced GaAs transparency near 1 micron. The Drude model can be applied to assist in selecting an anti-reflective coating. If the model predicts that the requirements of an application cannot be met by a doped layer alone, a doped layer can be applied that exceeds the required IR transparency, and a metallic grid can be applied to improve the EMI shielding, thereby satisfying the requirements.