Semiconductor Absorber Structure for Broadband Infrared Absorption
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Solution Overview
Problem
Existing absorbing artificial electromagnetic metamaterials face challenges with narrow absorption bands and high material and processing complexity, limiting their application in fields requiring multi-spectral imaging and thermal radiation detection.
Innovation Solution
A semiconductor absorber structure doped with specific conductivity types, featuring a dielectric layer and a buried semiconductor structure, optimized through doping concentrations and geometric parameters, achieving broadband and broad-angle absorption from 3 μm to 12 μm with high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a periodic perfectly absorbing structure is used to achieve high absorption efficiency, then the absorption rate reaches nearly 100% at resonance frequency, but the absorption band becomes narrow and limited to a single frequency band
Solution Approach 1:
The absorber is divided into multiple functional layers with distinct purposes: a top metal pattern layer for resonance, a middle dielectric layer for impedance matching, and a bottom metal ground layer for reflection. This segmentation allows each layer to be optimized independently, achieving high absorption efficiency at specific frequencies while maintaining structural simplicity
Solution Approach 2:
The patent employs periodic variation of geometric parameters (pattern size, spacing, layer thickness) across different regions of the absorber structure. By changing these parameters, the resonance frequencies are tuned to create multiple absorption bands, thus widening the overall absorption bandwidth while maintaining high absorption efficiency at each band
2Adaptability or versatility
If multiple materials and layers are stacked to achieve wide-band absorption (5.5-7.0 μm with 80% absorption), then the absorption bandwidth increases, but the structure becomes costly and challenging to process
Solution Approach 1:
The patent uses a universal metallic ground layer that serves multiple functions: providing electromagnetic reflection, enabling impedance matching, and acting as a structural support base. This multi-functionality reduces the need for additional specialized layers, simplifying fabrication while maintaining wide-band absorption capabilities
Solution Approach 2:
The absorber employs a composite structure combining metal patterns, dielectric materials, and metallic ground layers. This composite approach allows optimization of electromagnetic properties in each layer while using commercially available materials that are easy to process, achieving wide-band absorption without excessive fabrication complexity
3Ease of manufacture
If a simple multi-layer structure with four layers is used, then the manufacturing complexity is reduced, but the absorption rate becomes weak in remaining frequency bands outside the three absorption peaks
Solution Approach 1:
The patent implements periodic modulation of the metal pattern geometry and spacing across the absorber structure. This periodic variation creates multiple resonance modes that generate absorption peaks at different frequencies, expanding absorption coverage across broader frequency bands while maintaining the simple four-layer structure for ease of manufacture
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 absorber achieves over 80% absorption across a wide bandwidth and insensitivity to incident angles, simplifying fabrication and reducing costs, suitable for thermal sensors and imaging applications.
Implementation Method 1
a semiconductor absorption structure doped with dopants of a first conductivity type, a semiconductor substrate doped with dopants of a second conductivity type different from the first conductivity type
Data Source
AI summary
An absorber and a method of forming an absorber. The absorber may include a semiconductor absorption structure doped with dopants of a first conductivity type. The absorber may also include a semiconductor substrate doped with dopants of a second conductivity type different from the first conductivity type. The absorber may further include a dielectric layer between the semiconductor absorption structure and the semiconductor substrate. The absorber may additionally include a buried semiconductor structure included in a cavity of the dielectric layer, the buried semiconductor structure doped with dopants of the first conductivity type.