Integrated NIR Photodiodes and LEDs for Low-Light Quantum Efficiency
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Solution Overview
Problem
Image detection systems in low-lighting environments face challenges due to the low quantum efficiency of silicon-based near-infrared (NIR) pixel sensor devices, which affects their performance in applications like medical imaging and remote sensing.
Innovation Solution
The integration of NIR LEDs, NIR photodiodes, and visible light (VIS) photodiodes on a single substrate using selectively grown epitaxial materials like silicon germanium (SiGe) or gallium arsenide (GaAs) enhances quantum efficiency and reduces manufacturing complexity and space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based photodiodes are used for NIR detection, then the device structure is simple and manufacturing is easier, but the quantum efficiency is low
Solution Approach 1:
The patent uses silicon germanium (SiGe) alloy material that combines silicon and germanium in specific ratios (e.g., Si80Ge20 to Si50Ge50) to create a composite semiconductor material. This composite material simultaneously achieves high quantum efficiency for NIR detection (greater than 70%) and compatibility with existing silicon-based manufacturing processes, resolving the contradiction between manufacturing simplicity and detection performance.
Solution Approach 2:
The patent changes the material composition parameters by adjusting the germanium content in silicon germanium alloys and optimizing crystal orientation parameters (e.g., <100>, <110>, <111> orientations). These parameter changes enable the photodiode to achieve peak quantum efficiency at specific NIR wavelengths (700-2500nm) while maintaining manufacturability through controlled material synthesis.
2Reliability
If discrete NIR LED and NIR pixel sensor devices are used, then the system has high performance, but the device space and manufacturing complexity increase
Solution Approach 1:
The patent merges the NIR light source (LED) and NIR detector (pixel sensor) into a single integrated device structure. The NIR LED and NIR photodiode are fabricated on the same substrate using the same silicon germanium material system, eliminating the need for separate discrete devices and reducing manufacturing complexity while maintaining high system performance for low-light imaging applications.
Solution Approach 2:
The silicon germanium material system serves multiple functions simultaneously: it acts as the active layer for NIR photodetection, as the material for NIR LED light emission, and as a compatible platform with existing silicon CMOS manufacturing processes. This multi-functionality reduces the need for separate specialized manufacturing lines for different components.
3Measurement precision
If discrete optoelectronic devices are used for low-light imaging, then the detection capability is sufficient, but the resource consumption and manufacturing operations increase
Solution Approach 1:
The patent combines multiple photodiodes with different crystal orientations (<100>, <110>, <111>) and material compositions into a single sensor array on one substrate. This merging approach maintains high detection capability across different NIR wavelengths while reducing the total number of separate manufacturing operations and resource consumption compared to producing multiple discrete sensor devices.
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 approach improves the quantum efficiency of NIR pixel sensor devices, increases manufacturing yield, and reduces resource consumption by minimizing device space and manufacturing operations, making it more efficient for low-light applications.
Implementation Method 1
CMOS image sensor (CIS) devices utilize light-sensitive CMOS circuitry to convert light energy into electrical energy. As the photodiode is exposed to light, an electrical charge is induced in the photodiode (referred to as a photocurrent).
Implementation Method 2
forming a near infrared light emitting diode in a first cavity by selectively growing a first epitaxial material in the first cavity; forming a near infrared photodiode in a second cavity by selectively growing a second epitaxial material in the second cavity
Data Source
AI summary
Some implementations described herein include an optoelectronic device for a low-lighting application and techniques to form the optoelectronic device. The optoelectronic device includes near infrared light emitting diodes, near infrared photodiodes, and visible light photodiodes combined in a single substrate. The near infrared light emitting diodes and the near infrared photodiodes are formed using a selectively grown epitaxial material. The selectively grown epitaxial material (e.g., silicon germanium, gallium arsenide, or another type III/V material) improves a quantum efficiency performance of the near infrared photodiode relative to another photodiode that may be formed through doping a silicon material.