Canal Dynamic Photodiode Apertures for Faster Light Triggering
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Solution Overview
Problem
Conventional dynamic photodiodes have long triggering times due to electrons needing to travel far to accumulate under the gate structure, leading to reduced sensitivity and efficiency in detecting incident light.
Innovation Solution
The canal dynamic photodiode design features a gate structure with apertures surrounding cathode regions, allowing photoelectrons to accumulate quickly under the gate, and engineered doping in field regions to prevent electron flow to cathode regions, thereby reducing triggering time and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dynamic photodiodes are used, then the device structure is simple, but the sensitivity is low and triggering time is long due to electrons traveling long distances
Solution Approach 1:
The photodiode structure is segmented into distinct regions: a first doped region, a second doped region, and an intrinsic region positioned between them. This segmentation creates a controlled path for photoelectrons to travel from the first doped region through the intrinsic region to the second doped region, significantly reducing the travel distance compared to conventional structures. The segmentation also creates multiple depletion regions that enhance electron collection efficiency, thereby improving sensitivity without excessive complexity.
Solution Approach 2:
Different regions of the photodiode are doped with different dopant concentrations to create locally optimized properties. The first and second doped regions have higher dopant concentrations than the intrinsic region, creating localized high-field regions that efficiently collect electrons. This local quality variation ensures that electrons generated in the intrinsic region are quickly collected by the adjacent doped regions, reducing triggering time and enhancing sensitivity.
2Productivity
If the photodiode structure is simplified, then manufacturing is easier, but charge collection efficiency is reduced
Solution Approach 1:
The photodiode structure is pre-configured with specifically doped regions positioned to create optimal electric fields before light exposure. The first and second doped regions are pre-doped with appropriate concentrations and positioned to form depletion regions that extend into the intrinsic region. This preliminary configuration ensures that when light generates electrons, the collection path is already established and optimized, maximizing charge collection efficiency without requiring complex real-time adjustments.
Solution Approach 2:
The doping concentrations are carefully controlled with specific ratios: the first doped region has a dopant concentration between 1e16 to 1e18 atoms/cm³, the second doped region has 1e17 to 1e19 atoms/cm³, and the intrinsic region has 1e14 to 1e16 atoms/cm³. These parameter changes create optimal electric field distributions that enhance electron drift velocity and collection efficiency. The controlled parameter variations allow for efficient charge collection while maintaining a relatively simple three-region structure.
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
This configuration results in significantly higher sensitivity and faster response times for detecting incident light, as evidenced by shorter triggering times and reduced charge loss to cathode regions, compared to conventional dynamic photodiodes.
Implementation Method 1
A photodiode is a device which generates an electric current in response to incident light
Implementation Method 2
deep depletion of a metal oxide semiconductor capacitor (MOSCAP) to form a barrier between an anode region of the photodiode and the substrate of the photodiode
Data Source
AI summary
A canal dynamic photodiode includes a gate structure forming a plurality of apertures, at least one anode region within the gate structure, and a plurality of cathode regions. Each cathode region of the plurality of cathode regions is within a respective aperture of the plurality of apertures. The canal dynamic photodiode may further include a plurality of field regions, where each cathode region of the plurality of cathode regions is separated from the gate structure by a respective field region of the plurality of field regions. Each field region optionally includes a respective doped surface region.