InGaAs Multispectral Sensor Structure for Low Crosstalk IR Imaging
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Solution Overview
Problem
Existing multispectral imaging technologies face challenges in miniaturization, high production costs, and crosstalk issues when attempting to analyze items in three dimensions and extend spectral analysis beyond the visible and near-infrared ranges, particularly for wavelengths greater than 1000 nm.
Innovation Solution
A hybrid multispectral imaging sensor is developed, featuring a photosensitive detector made on an indium phosphide (InP) substrate with an indium gallium arsenide (InGaAs) structure and a filter module composed of Fabry-Pérot filters, where the filter module is formed on a separate substrate and bonded to the detector, minimizing crosstalk by reducing the InP substrate thickness and using alignment patterns and crosstalk barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the InP substrate thickness is reduced to minimize crosstalk, then crosstalk is reduced, but the mechanical strength and handling robustness of the substrate deteriorate
Solution Approach 1:
The patent employs a composite structure combining InP substrate with InGaAs detector layers and additional support layers. This composite approach allows the thin InP substrate (reduced to minimize crosstalk) to be reinforced by the combined structural integrity of the multi-layer composite system, thereby maintaining mechanical strength while achieving low crosstalk performance.
Solution Approach 2:
The patent introduces intermediary support structures and bonding layers between the thin InP substrate and the detector array. These intermediary elements provide mechanical support to the weakened thin substrate during handling and operation, enabling the substrate to be sufficiently thin for crosstalk reduction while preventing mechanical failure.
2Adaptability or versatility
If a filter module is added to enable multispectral imaging, then spectral analysis capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the filter module with the detector array into a single integrated hybrid sensor. The filters are positioned in direct contact with or very close to the detector pixels, combining the spectral filtering function with the detection function in one unified structure. This integration reduces the overall system complexity compared to separate filter and detector components.
Solution Approach 2:
The filter module is designed to provide multiple spectral bands simultaneously across the entire detector array, enabling the sensor to perform multispectral imaging across different wavelength ranges (visible, near-infrared, and short-wave infrared) with a single device configuration, rather than requiring separate specialized sensors for each band.
3Adaptability or versatility
If the sensor is designed for wavelengths greater than 1000 nm, then infrared detection capability is improved, but sensitivity and signal quality deteriorate due to crosstalk
Solution Approach 1:
The patent segments the detector array into individually isolated pixels with deep potential wells that prevent charge carrier diffusion between adjacent pixels. This segmentation approach isolates the detection regions, preventing crosstalk while maintaining sensitivity for infrared wavelengths greater than 1000 nm.
Solution Approach 2:
The patent modifies the detector parameters by adjusting the depth and dimensions of the potential wells in the InGaAs layer, optimizing the electric field distribution to confine charge carriers within each pixel region. This parameter optimization maintains high signal quality and prevents crosstalk in the long-wave infrared region.
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 sensor effectively operates for wavelengths from 1000 nm to 2200 nm with reduced crosstalk, enabling efficient multispectral imaging across a broader infrared range while maintaining sensitivity and fabrication yield.
Implementation Method 1
a filter module which is formed on a second substrate on which the first mirror, the spacer, and the second mirror have been deposited, in that order
Implementation Method 2
Certain spectrometers use at least one Fabry-Pérot filter. It should be noted or recalled that such a filter is constituted by a parallel-face 'plate' of a material (usually of low refractive index, such as air, silica, etc.) forming a 'spacer' between two mirrors
Implementation Method 3
a photosensitive backside-illumination detector that is made on a first substrate made of InP and having a backside face and a frontside face, and that is formed of a matrix of pixels that are themselves made in a structure based on InGaAs
Implementation Method 4
a photosensitive backside-illumination detector that is made on a first substrate made of InP and having a backside face and a frontside face, and that is formed of a matrix of pixels that are themselves made in a structure based on InGaAs, and deposited by epitaxy on the frontside face of the first substrate made of InP
Data Source
AI summary
A hybrid multispectral imaging sensor, characterized in that it comprises a photosensitive backside-illumination detector (DET) that is made on a substrate (100) made of InP, and that is formed of a matrix of pixels (105, P1, P2, P3) that are themselves made in a structure based on InGaAs (103), and a filter module (MF) that is formed of a matrix of elementary filters (λ1, λ2, λ3) reproducing said matrix of pixels, and that is mounted into contact with said substrate (100), said substrate (100) made of InP having a thickness less than 50 μm, and preferably less than 30 μm.