Photodiode Array Charge-Absorbing Doped Region
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Solution Overview
Problem
InGaAs photodiode arrays face a blooming phenomenon, leading to loss of spatial resolution in high-light conditions, and existing solutions like electric insulation through etching result in increased dark current and manufacturing complexities.
Innovation Solution
A photodiode array structure with a cathode layer of indium phosphide and an active layer of indium-gallium arsenide, featuring doped regions that absorb excess charge carriers and are biased to reduce parasitic currents, allowing for improved image quality without spatial resolution loss, even under strong optical intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electric insulation through etching is used to prevent blooming, then blooming phenomenon is reduced, but dark current increases and manufacturing complexity increases
Solution Approach 1:
The patent introduces an intermediary doped region between adjacent photodiodes that acts as a charge sink to absorb excess carriers and prevent lateral conductivity. This intermediary structure prevents blooming without the need for etching, thereby avoiding the increase in dark current and manufacturing complexity that would result from etching-based solutions.
2Object-affected harmful factors
If electric insulation through etching is used to prevent blooming, then blooming phenomenon is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent merges the blooming prevention function into the existing photodiode structure by forming doped regions during the same manufacturing process steps used for creating the photodiodes themselves. This integration eliminates the need for separate etching and insulation steps, thereby preventing blooming without increasing manufacturing complexity.
3Illumination intensity
If photodiode array operates in high-light conditions, then detection capability is maintained, but spatial resolution is lost due to blooming
Solution Approach 1:
The patent applies local quality by creating doped regions with specific electrical properties in localized areas between photodiodes. These regions have different doping concentrations and carrier absorption characteristics tailored to prevent lateral charge diffusion in high-light conditions, thereby maintaining spatial resolution while preserving detection capability under strong optical intensities.
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 proposed structure effectively reduces lateral conductivity and maintains image quality in integration mode, preventing blooming and minimizing dark current issues, while simplifying the manufacturing process by using a single selective doping step.
Implementation Method 1
at least one second doped region to absorb charge carriers emitted by the photodiodes
Implementation Method 2
with suitable doping, the two heterojunctions between the active layer and the two protection/passivation layers confine the photoelectric charges within the active detection layer and improve the quantum yield of the photodiode thus constructed
Data Source
AI summary
The invention concerns a photodiode array, and the method for producing same, comprising—a cathode comprising at least one substrate layer (4) made from a material from the indium phosphide family and one active layer (5) made from a material from the gallium indium arsenide family, and characterized in that the array further comprises at least two sorts of doped regions of the same type at least partially formed in the active layer (5):—first doped regions (3) forming, with the cathode, photodiodes for forming images,—at least one second doped region (8) absorbing excess charge carriers so as to discharge them.