Single Photon Detection Element Guard Ring Design
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Solution Overview
Problem
Single Photon Avalanche Diodes (SPADs) suffer from noise signals and after-pulse phenomena due to defects in the manufacturing process, leading to reduced frame rate and signal-to-noise ratio (SNR) and increased dead time.
Innovation Solution
A single photon detection device design featuring a first well, a second well, a heavily doped region, and a guard ring with specific doping concentrations and geometries to minimize noise and after-pulse occurrences, with the guard ring extending to the side surface of the second well and the contact facing the heavily doped region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dead time is increased to prevent after-pulse phenomenon, then the reliability is improved, but the productivity is reduced
Solution Approach 1:
The patent extracts and removes defect sites from the active detection region by forming a guard ring structure that isolates defective areas. This allows the system to maintain high frame rates while preventing after-pulse phenomena from defective regions, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent applies different doping concentrations and structural configurations to different regions of the detector. The guard ring region has specific doping characteristics that differ from the active detection region, allowing local suppression of after-pulse phenomena without affecting the overall detection performance and frame rate.
2Reliability
If the noise signals are reduced by increasing dead time, then the signal-to-noise ratio is improved, but the frame rate is reduced
Solution Approach 1:
The guard ring structure extracts and isolates noise-generating defect sites from the active detection region. This enables the system to maintain high frame rates while achieving improved signal-to-noise ratio by preventing noise from defective areas from contaminating the detection signal.
Solution Approach 2:
The patent implements preliminary anti-action by proactively isolating potential noise sources through the guard ring structure before they can affect the detection signal. This prevents after-pulse phenomena and noise generation at their source, allowing high frame rates to be maintained without compromising signal-to-noise ratio.
3Manufacturing precision
If the guard ring structure is added to reduce defects, then the manufacturing precision is improved, but the device complexity is increased
Solution Approach 1:
The guard ring structure implements local quality by applying specific doping concentrations and geometric configurations only to the guard ring region, while leaving the active detection region unchanged. This targeted approach reduces defects effectively while adding minimal structural complexity to the overall device.
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 design reduces noise and after-pulse phenomena, resulting in a lower dead time and improved SNR, enabling more efficient photon detection.
Implementation Method 1
When a photon with enough energy to release the electron reaches the photo diode, an electron-hole pair (EHP) is generated
Implementation Method 2
The high electric field accelerates the photo-generated electrons quickly to (+) side, and the additional electrons-hole pairs are generated in succession by the impact ionization by such acceleration electrons. And then the electrons accelerate to the anode
Implementation Method 3
the additional electrons-hole pairs are generated in succession by the impact ionization by such acceleration electrons
Data Source
AI summary
Disclosed is a single photon detection device comprises a first well, a second well provided on the first well, a heavily doped region provided on the second well, and a contact facing the heavily doped region. The first well, the second well, and the contact have a first conductive type. The heavily doped region has a second conductive type that is different from the first conductive type. The region between the heavily doped region and the contact consist of semiconductor materials.