Photodiode Doping Profile Reshapes Electric Field to Suppress Dark Current
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Solution Overview
Problem
Photodiodes suffer from reduced sensitivity due to unwanted dark current, which degrades detection accuracy and image quality, especially when used in image sensors.
Innovation Solution
A photodiode device with an anti-reflection structure and a specific doping profile is designed to enhance photon reception efficiency and reduce dark current by reshaping the electric field distribution around the PN junction, using a third doped region with a higher doping concentration to minimize the depletion region's size and prevent it from contacting the anti-reflection structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photodiode is designed with conventional structure, then it can convert photons to electrical current, but dark current increases and sensitivity decreases
Solution Approach 1:
The patent introduces a third doped region with higher doping concentration specifically at the periphery of the second doped region, creating localized high-concentration zones that reshape the electric field distribution. This local modification reduces dark current generation at critical areas without affecting the overall photodiode structure, thereby improving detection accuracy while suppressing harmful dark current.
Solution Approach 2:
The patent modifies the doping concentration parameter by introducing a third doped region with higher doping concentration than the second doped region. This parameter change reshapes the electric field distribution and reduces the depletion region size, effectively suppressing dark current while maintaining photon-to-current conversion efficiency.
2Productivity
If the depletion region is enlarged to improve photon reception, then quantum efficiency increases, but dark current increases and sensitivity decreases
Solution Approach 1:
The third doped region is strategically positioned at the periphery of the second doped region, creating localized high-concentration zones that reshape the electric field distribution. This local modification reduces dark current generation at critical areas without affecting the overall photodiode structure, thereby improving detection accuracy while suppressing harmful dark current.
Solution Approach 2:
The patent modifies the doping concentration parameter by introducing a third doped region with higher doping concentration than the second doped region. This parameter change reshapes the electric field distribution and reduces the depletion region size, effectively suppressing dark current while maintaining photon-to-current conversion efficiency.
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 solution significantly reduces dark current and improves sensitivity, allowing for enhanced photon-current generation and effective operation in high-speed applications.
Implementation Method 1
Photodiodes are used in converting received photons into electrical currents
Implementation Method 2
a specific doping profile is designed to enhance photon reception efficiency and reduce dark current by reshaping the electric field distribution around the PN junction
Data Source
AI summary
The present disclosure provides a photodiode device, which includes a semiconductor substrate, a well region in the semiconductor substrate of a first dopant type, a first doped region of the first dopant type in the well region, and a second doped region of a second dopant type disposed in the well region and over the first doped region. The second doped region comprises first recesses exposed through a surface of the second doped region, and a first portion of the second doped region on the surface comprises a first doping concentration of the second dopant type greater than a second doping concentration of a second portion of the second doped region away from the first recesses.