Back-Illuminated InGaAs Detector Stack for Wideband SWIR Sensing
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Solution Overview
Problem
Existing electromagnetic radiation detectors struggle to effectively detect a wide band of electromagnetic radiation wavelengths, particularly in the short-wave infrared (SWIR) range, with high signal-to-noise ratio (SNR) and extended absorption range.
Innovation Solution
The development of wideband back-illuminated electromagnetic radiation detectors using an indium phosphide (InP) substrate with stacked indium gallium arsenide (InGaAs) absorbers and buffer layers, allowing for the absorption of a wide range of electromagnetic radiation wavelengths, including SWIR wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single absorber material is used in electromagnetic radiation detectors, then the detector structure remains simple, but the absorption range and signal-to-noise ratio are limited
Solution Approach 1:
The detector is divided into multiple absorber layers (first InGaAs absorber and second InGaAs absorber) with different bandgaps, where each layer absorbs specific wavelength ranges. This segmentation allows the detector to cover a broader spectral range while maintaining manageable structural complexity through systematic layering.
Solution Approach 2:
The detector employs composite material structure combining InP substrate with multiple InGaAs absorber layers having different compositions (different indium and gallium ratios). This composite approach enables tailored absorption characteristics for different SWIR wavelength bands, extending the overall absorption range while maintaining structural integrity.
2Reliability
If existing detector configurations are used, then manufacturing processes remain straightforward, but the signal-to-noise ratio and detection effectiveness in SWIR range are insufficient
Solution Approach 1:
Different regions of the detector are designed with locally optimized properties: the first InGaAs absorber layer has specific composition for absorbing shorter SWIR wavelengths, while the second InGaAs absorber layer has different composition for longer SWIR wavelengths. This local quality optimization ensures high signal-to-noise ratio across the entire SWIR spectrum by matching material properties to specific detection requirements.
Solution Approach 2:
The detector utilizes parameter changes in the InGaAs material composition (varying indium and gallium ratios) to tune the bandgap and absorption characteristics of each layer. By changing these material parameters, the detector achieves optimized signal-to-noise ratio for different wavelength ranges while maintaining a relatively systematic device configuration.
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 configuration enhances the detectors' ability to detect electromagnetic radiation across a broad spectral range with improved SNR and extended absorption range, effectively addressing the limitations of existing detectors.
Implementation Method 1
a first indium gallium arsenide (InGaAs) electromagnetic radiation absorber stacked on the first surface and configured to absorb a first set of electromagnetic radiation wavelengths
Implementation Method 2
a set of one or more buffer layers stacked on the first InGaAs electromagnetic radiation absorber and configured to absorb at least some of the first set of electromagnetic radiation wavelengths
Implementation Method 3
a second InGaAs electromagnetic radiation absorber stacked on the set of one or more buffer layers and configured to absorb a second set of electromagnetic radiation wavelengths
Implementation Method 4
an immersion condenser lens formed on the second surface and configured to direct electromagnetic radiation through the InP substrate
Implementation Method 5
an immersion condenser lens formed on the second surface and configured to direct electromagnetic radiation through the InP substrate
Data Source
AI summary
An electromagnetic radiation detector includes an InP substrate having a first surface opposite a second surface; a first InGaAs electromagnetic radiation absorber stacked on the first surface and configured to absorb a first set of electromagnetic radiation wavelengths; a set of one or more buffer layers stacked on the first InGaAs electromagnetic radiation absorber and configured to absorb at least some of the first set of electromagnetic radiation wavelengths; a second InGaAs electromagnetic radiation absorber stacked on the set of one or more buffer layers and configured to absorb a second set of electromagnetic radiation wavelengths; and an immersion condenser lens formed on the second surface and configured to direct electromagnetic radiation through the InP substrate and toward the first InGaAs electromagnetic radiation absorber and the second InGaAs electromagnetic radiation absorber.