Hybrid APD Photodetector for Precise Radiation Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photodetectors struggle to accurately detect weak light radiation and provide precise determination of radiation levels, especially in applications with uneven radiation distribution across the exposure panel.
Innovation Solution
A photodetector design incorporating a combination of avalanche photodiodes (APDs) and non-amplifying photodiodes, where APDs are operated in Geiger mode for high sensitivity and fast response, and non-amplifying photodiodes provide temperature-independent quantitative detection with high signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If avalanche photodiodes are operated in Geiger mode for high sensitivity detection, then single photon detection capability is improved, but the ability to quantitatively determine radiation levels deteriorates due to saturation of the avalanche breakdown
Solution Approach 1:
The photodetector is divided into multiple independent detection regions: Geiger-mode APD pixels for single photon sensitivity and non-amplifying photodiode regions for quantitative measurement. Each region performs its specialized function independently, and the results are combined to achieve both single photon detection capability and quantitative radiation level determination.
Solution Approach 2:
The patent combines Geiger-mode APD pixels and non-amplifying photodiodes into a single integrated photodetector structure. The Geiger-mode regions provide high sensitivity for detecting weak light radiation, while the non-amplifying regions provide temperature-independent quantitative detection, merging the advantages of both detection modes.
2Measurement precision
If avalanche photodiodes are used for high sensitivity detection, then detection capability for weak light radiation is improved, but temperature dependence increases affecting measurement stability
Solution Approach 1:
The photodetector structure segments the detection function into two independent parts: Geiger-mode APD pixels that are temperature-sensitive but provide high sensitivity detection, and non-amplifying photodiodes that are temperature-independent and provide stable reference measurements. This segmentation allows each component to optimize for its specific function.
Solution Approach 2:
The patent changes the operating parameters of different detection regions: Geiger-mode APDs operate with bias voltage at or above breakdown voltage for high gain, while non-amplifying photodiodes operate with bias voltage well below breakdown voltage for temperature-independent operation. This parameter differentiation resolves the temperature stability issue while maintaining high sensitivity.
3Area of stationary object
If multiple GM-APDs are combined in multipixel photodetectors to extend detection area, then detection area is improved, but device complexity increases due to need for combining multiple photocurrents
Solution Approach 1:
The patent merges Geiger-mode APD pixels and non-amplifying photodiodes into a single integrated photodetector structure with unified readout electronics. This integration simplifies the combination of signals from multiple detection elements compared to traditional MPPC architectures, reducing device complexity while maintaining large detection area.
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 combination enables precise determination of total radiation levels, improved energy resolution, and reduced temperature dependence, enhancing measurement accuracy and efficiency in applications with varying radiation distributions.
Implementation Method 1
In an avalanche photodiode (APD), the bias voltage is approximately as high as or higher than the avalanche breakdown voltage, so that the created charge carriers, in turn, create further charge carriers.
Implementation Method 2
Photodetectors convert received light into an electrical signal. In a semiconductor photodetector, a photon of sufficient energy generates an electron-hole pair in a semiconductor body electrically biased by two electrodes.
Data Source
AI summary
A photodetector (90) having an exposure surface (91) has a first photodiode array (1) having a first light entry surface (11) and a second photodiode array (2) having a second light entry surface (21). The first photodiode array (1) has an avalanche photodiode (10). The second photodiode array (2) has a non-amplifying photodiode (10). The first light entry surface (11) and the second light entry surface (21) form sub-surfaces of the exposure surface (91).