Cycling Excitation Process Photodetector for NIR LiDAR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LiDAR systems face limitations in sensitivity, resolution, and operational speed due to the sensitivity of detector arrays to IR wavelengths, high dark count rates, and long dead times in Geiger mode avalanche photodetectors, which hinder their performance in applications like autonomous driving and space remote sensing.
Innovation Solution
The development of a photodetector with a novel carrier multiplication mechanism called Cycling Excitation Process (CEP) and a self-quenching, self-recovering structure using a bandgap engineered InGaAsP/InP/InGaAsP heterostructure and a-Si gain medium, which reduces excess noise and eliminates the need for complex quenching circuits, enabling high sensitivity and continuous operation at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Geiger mode avalanche photodetectors are used to achieve single photon sensitivity, then sensitivity is improved, but dead time increases to microseconds limiting continuous operation
Solution Approach 1:
The patent transitions from static Geiger mode operation to dynamic sub-Geiger mode operation, where the detector operates in a continuously responsive state rather than alternating between detection and dead time periods. This dynamic operation mode allows the detector to maintain single photon sensitivity while eliminating the microsecond dead time limitation.
Solution Approach 2:
The patent changes the operating parameters from Geiger mode (above breakdown voltage) to sub-Geiger mode (below breakdown voltage), fundamentally altering the detection mechanism. This parameter change enables continuous operation by avoiding the complete carrier multiplication and subsequent reset cycle that causes dead time in Geiger mode.
2Reliability
If InGaAsP/InP/InGaAsP heterostructure is used to extend wavelength sensitivity into infrared regime, then sensitivity to IR wavelengths is improved, but dark count rate increases due to higher defect density
Solution Approach 1:
The patent applies local quality by creating distinct functional regions within the detector structure. The InGaAsP absorption layer is optimized for IR photon absorption while the InP multiplication region is engineered with lower defect density for carrier multiplication. This spatial separation of functions allows IR sensitivity without proportionally increasing dark count rate.
Solution Approach 2:
The patent uses a composite heterostructure combining InGaAsP and InP materials, each contributing different properties. The InGaAsP layer provides IR wavelength sensitivity while the InP layer provides low-defect carrier multiplication. This composite approach achieves IR sensitivity while managing dark count rate through material property optimization.
3Ease of operation
If complex quenching circuits are implemented in readout integrated circuit to reset Geiger mode pixels, then detection recovery is improved, but device complexity and chip area increase
Solution Approach 1:
The patent implements self-service by designing the detector to automatically recover from detection events without external quenching circuits. The sub-Geiger mode operation inherently prevents complete carrier multiplication, allowing natural carrier recombination and automatic reset. This eliminates the need for complex active quenching and resetting circuits, reducing chip area and simplifying the readout integrated circuit.
4Reliability
If bulk Si SPADs with thick Si layer are used to absorb NIR light, then photon detection efficiency is improved, but operation speed decreases due to long diffusion length
Solution Approach 1:
The patent segments the detector into two distinct functional layers: an InGaAsP absorption layer optimized for NIR photon absorption and an InP multiplication region optimized for fast carrier multiplication. This segmentation allows each layer to be optimized for its specific function, achieving high photon detection efficiency without sacrificing operation speed, as the absorption and multiplication processes occur in separate, optimized regions.
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 CEP mechanism achieves efficient carrier multiplication with lower operation voltage and reduced timing jitter, while the self-quenching and self-recovering design simplifies the readout integrated circuit, enhancing the detector's sensitivity and dynamic range, and allowing for sub-Geiger mode operation with low afterpulsing and high gain-bandwidth product.
Implementation Method 1
The CEP mechanism achieves efficient carrier multiplication with lower operation voltage and reduced timing jitter
Implementation Method 2
a light absorbing layer of InGaAsP
Data Source
AI summary
High speed, and high timing resolution photon detecting systems and methods are presented with multiplication and self-quenching and self-recovering functions.