Hybrid Optical Detector Unit for Multispectral Imaging
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Solution Overview
Problem
Conventional optical detector blocks are limited to infrared operation, suffer from resolution constraints due to narrow detector width, and have reduced sensitivity due to electrical interconnection holes, which affect image interpretation and identification.
Innovation Solution
An optical detector block with a hybrid architecture integrating a second optical detector and reading circuit for extended wavelength range, featuring a common reading circuit with electrodes connected through semiconductor structures and annular doped zones, along with metal patches for improved light confinement and reduced dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the width of elementary detectors is reduced to increase resolution, then the number of detectors per area increases, but crosstalk between detectors increases due to closer proximity of electrical contacts and NP junctions
Solution Approach 1:
The patent moves the electrical contact from the front surface to the back surface of the semiconductor structure. This spatial relocation in the depth dimension allows detectors to be placed closer together in the planar dimension without increasing crosstalk, as the front-facing NP junctions are no longer in close proximity to each other's electrical contacts.
Solution Approach 2:
The patent inverts the conventional architecture by placing the electrical contact on the back of the detector rather than the front. This inversion allows the light-sensitive NP junction to remain on the front surface while the electrical contact is relocated to the back, eliminating the crosstalk issue that arises from front-surface contacts being too close together.
2Reliability
If electrical interconnection holes are present on the surface of elementary detectors, then electrical contact is established, but the filling rate and sensitivity are reduced
Solution Approach 1:
The patent relocates the electrical interconnection hole from the front surface to the back surface of the semiconductor structure. This allows the entire front surface to be available for light detection, maximizing the filling rate and sensitivity, while electrical contact is maintained through the back surface.
3Adaptability or versatility
If the passivation layer is removed to extend operation into the visible spectrum, then spectral range is extended, but image contrast changes making interpretation difficult
Solution Approach 1:
The patent divides the optical detector into two separate structures: one optimized for infrared detection with passivation layer and NP junction configuration, and another for visible detection. Each detector type maintains its optimal structure for its designated wavelength range, allowing both spectral ranges to be covered without compromising image quality in either range.
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
Enables multispectral detection with improved resolution and sensitivity, allowing for enhanced image processing and identification across visible and infrared spectrums, while maintaining compact dimensions and optimized performance.
Implementation Method 1
each detection element being intended to transform a flow of incident photons into an electrical signal
Implementation Method 2
at least one metallic patch, disposed in contact with the semiconductor structure and suitable for optical confinement of the incident light flux within the semiconductor structure
Data Source
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AI summary
This optical detector unit is a hybrid unit operating in a given wavelength range and comprises, superposed: a first optical detector (12) comprising detecting elements (18) formed in a semiconductor structure (20), each detecting element (18) being intended to convert a flux of incident photons into an electrical signal; and a first read circuit for reading the electrical signal from each detecting element (18). The optical detector unit (10) furthermore comprises an imaging system (14) comprising a second optical detector (28) intended to increase the operating wavelength range of the optical detector unit (10) and a second read circuit for reading electrical signals from detecting elements (18) of the second optical detector (28). The first and second read circuit are integrated together, so as to form a common read circuit (30).