Photodiode Layer Structure for Low Dark Current NIR Detection
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Solution Overview
Problem
Conventional photodiode devices suffer from high dark current rates and susceptibility to premature breakdown, which limits their performance in applications such as near-infrared photon detection.
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 narrower than the multiplication layer and the absorption layer is wider, reducing dark counts and premature breakdown by guiding electrons into a specific region of the multiplication layer and separating the absorption and multiplication layers with a dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photodiode devices use a PN junction with reverse bias to detect photons, then photon detection capability is achieved, but dark current rates become high
Solution Approach 1:
The photodiode device is segmented into distinct functional layers: an absorption layer for photon absorption, a charge layer for carrier separation and storage, and a multiplication layer for signal amplification. This segmentation allows each layer to be optimized independently, with the charge layer acting as a buffer to reduce dark current propagation to the multiplication layer, thereby maintaining photon detection capability while reducing dark current rates
Solution Approach 2:
The charge layer serves as an intermediary between the absorption layer and the multiplication layer. It accumulates and holds charge carriers generated in the absorption layer, preventing direct transmission of dark current to the multiplication layer. This intermediary structure enables the device to maintain high photon detection efficiency while significantly reducing the harmful effect of dark current
2Measurement precision
If conventional photodiode devices operate at high reverse bias to improve detection sensitivity, then photon detection sensitivity is improved, but premature breakdown occurs more frequently
Solution Approach 1:
The device structure segments the high-field region (multiplication layer) from the absorption region, with the charge layer acting as a buffer zone. This allows the multiplication layer to operate at high reverse bias for sensitive detection while the charge layer protects against premature breakdown by controlling electric field distribution and preventing field concentration at interfaces
Solution Approach 2:
The invention changes the electrical parameter distribution by introducing the charge layer with specific doping characteristics, which modifies the electric field profile across the device. This parameter change allows the multiplication layer to sustain higher reverse bias voltages for improved sensitivity without causing premature breakdown, as the charge layer regulates the field distribution
3Object-generated harmful factors
If the charge layer width is reduced to guide electrons into a specific region, then dark counts are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the charge layer width parameter to a specific range that effectively guides electrons into the multiplication layer while minimizing dark counts. By establishing this optimized parameter, the design balances the reduction of harmful dark current with practical manufacturing capabilities, avoiding excessive precision requirements
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, resulting in improved performance for near-infrared photon detection without compromising quantum efficiency.
Implementation Method 1
a multiplication layer disposed in the semiconductor substrate and having a first width
Implementation Method 2
an absorption layer disposed over the charge layer and having a third width
Data Source
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.