Infrared Light-Receiving Device Dark Current Suppression
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Solution Overview
Problem
Current light-receiving devices, particularly those using InGaAs films for infrared image sensors, face challenges in suppressing dark current generation due to crystal defects at the periphery of the InP and InGaAs films, which affect image quality and noise levels.
Innovation Solution
A light-receiving device is designed with a photoelectric conversion layer and a first semiconductor layer, where a second conductivity-type region is formed in the middle region of the first semiconductor layer, excluding the periphery, to minimize crystal defects and reduce dark current generation. This configuration includes a compound semiconductor with a first conductivity type for infrared absorption and a surrounding insulation layer to separate the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a p-n junction is formed using conventional methods with InP and InGaAs films, then photoelectric conversion is achieved, but crystal defects occur at the periphery causing dark current generation
Solution Approach 1:
The patent segments the semiconductor layer into a first semiconductor layer (InP) and a second semiconductor layer (InGaAs) with distinct functions. The first layer provides a defect-free p-n junction formation area in its middle region, while the second layer handles photoelectric conversion. This segmentation allows the p-n junction to be formed away from the defective periphery of the InGaAs film, thereby suppressing dark current while maintaining manufacturing feasibility.
Solution Approach 2:
The first semiconductor layer (InP) acts as an intermediary layer between the substrate and the second semiconductor layer (InGaAs). It provides a buffer zone that isolates the p-n junction formation from the crystal defects present in the InGaAs film periphery. The intermediary layer enables high-quality junction formation without direct exposure to the defective regions, thus improving reliability.
2Area of stationary object
If the InP wafer diameter is increased to improve sensor performance, then manufacturing cost and technical difficulty increase
Solution Approach 1:
The patent employs a composite structure combining InP and InGaAs films in specific layers. This composite material approach allows the use of smaller, more cost-effective InP wafers while achieving the desired sensor performance through optimized material composition and layer configuration. The composite structure maximizes the utility of smaller wafers by strategic material placement.
3Area of stationary object
If the InP wafer diameter is increased to improve sensor performance, then technical difficulty increases
Solution Approach 1:
By segmenting the semiconductor structure into functional layers with the p-n junction formed in the middle region of the first semiconductor layer, the patent avoids the need for large-wafer processing. This segmentation simplifies the manufacturing process by using standard-sized wafers with controlled defect distribution, thereby reducing technical difficulty while maintaining performance.
4Ease of manufacture
If a p-n junction is formed at the periphery of the semiconductor layer, then manufacturing is simpler, but crystal defects increase causing dark current
Solution Approach 1:
The patent applies local quality by forming the p-n junction specifically in the middle region of the first semiconductor layer, where crystal quality is highest and defect density is lowest. This localized approach to junction formation prioritizes reliability in the critical detection area, while accepting that periphery regions have higher defect density. The local quality principle ensures that the most important functional area operates with minimal defects.
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 effectively suppresses dark current generation and improves image quality by forming a p-n junction with fewer crystal defects, enhancing the performance of the light-receiving device and electronic apparatuses that utilize these sensors.
Implementation Method 1
a photoelectric conversion layer that includes a first compound semiconductor with a first conductivity type and absorbs a wavelength of an infrared region to generate electric charges
Data Source
AI summary
A light-receiving device of an embodiment of the present disclosure includes a photoelectric conversion layer that includes a first compound semiconductor with a first conductivity type and absorbs a wavelength of an infrared region, a first semiconductor layer formed on the photoelectric conversion layer, and an insulation layer formed to surround the photoelectric conversion layer and the first semiconductor layer, the first semiconductor layer having a second conductivity-type region at a middle region excluding a periphery facing the photoelectric conversion layer.