Photodiode Layer Structure to Reduce Dark Current and Breakdown
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Solution Overview
Problem
Conventional photodiode devices have high dark current rates and are susceptible to premature breakdown, which limits their performance in applications such as biosensing and optical communications.
Innovation Solution
A photodiode device structure comprising a semiconductor substrate with a multiplication layer, a dielectric layer, and an absorption layer, where the charge layer is smaller than the multiplication layer and the absorption layer is larger, reducing dark counts and preventing premature breakdown by guiding electrons and separating absorption and multiplication layers effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photodiode devices use a PN junction with reverse bias to detect photons, then photon detection capability is achieved, but dark current rate increases
Solution Approach 1:
The photodiode device is segmented into three distinct layers with different widths: an absorption layer, a charge layer, and a multiplication layer. This segmentation allows each layer to perform its specific function optimally - the absorption layer captures photons, the charge layer collects and transports carriers, and the multiplication layer amplifies the signal, thereby reducing dark current while maintaining detection capability
Solution Approach 2:
Each layer is assigned different local properties and widths tailored to its specific function. The absorption layer has a width optimized for photon absorption, the charge layer has a width optimized for carrier collection, and the multiplication layer has a width optimized for signal amplification. This local optimization reduces dark current in the charge layer while maintaining overall detection performance
2Object-generated harmful factors
If the charge layer width is reduced to lower dark current, then dark count rate decreases, but quantum efficiency may be compromised
Solution Approach 1:
The charge layer is designed with an optimized width that balances dark current reduction and carrier collection efficiency. By carefully controlling the charge layer width relative to the absorption and multiplication layers, the structure achieves low dark count rates while maintaining high quantum efficiency through effective carrier transport from the absorption to the multiplication layer
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 enhances quantum efficiency and reduces dark counts and premature breakdown, improving the overall performance of the photodiode device for near-infrared photon detection.
Implementation Method 1
an absorption layer disposed over the charge layer and having a third width greater than the second width of the charge layer
Implementation Method 2
a multiplication layer disposed in the semiconductor substrate and having a first width
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A photodiode device may include a semiconductor substrate, a multiplication layer disposed in the semiconductor substrate and having a first width, a dielectric layer disposed over the multiplication layer, a charge layer coupled to the multiplication layer and having a second width, and an absorption layer disposed over the charge layer and having a third width. The second width of the charge layer may be smaller than the first width of the multiplication layer, and the third width of the absorption layer may be greater than the second width of the charge layer.