Compound Semiconductor Imaging Structure for Low Dark Current
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Solution Overview
Problem
In imaging devices with compound semiconductors, the interfaces between different semiconductor layers can lead to increased interface states, resulting in higher dark current and potential deterioration of the light receiving element's characteristics.
Innovation Solution
The imaging device incorporates a support substrate with a first compound semiconductor, a photoelectric conversion layer with a second compound semiconductor, and protective layers with different compositions in trenches penetrating the substrate and conversion layer. This configuration allows for the optimization of interface states between the photoelectric conversion layer and the protective layers, reducing dark current and maintaining the element's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single protective layer material is used for both the photoelectric conversion layer and the support substrate, then the manufacturing process is simplified, but the interface states at both interfaces cannot be simultaneously minimized, leading to increased dark current
Solution Approach 1:
The patent applies different protective layer materials to different regions/interfaces: a first protective layer material is used for the interface with the photoelectric conversion layer, while a second protective layer material is used for the interface with the support substrate. This local differentiation allows each interface to be optimized independently, minimizing interface states at both interfaces and reducing dark current, while still using a unified layer structure that maintains manufacturing simplicity.
Solution Approach 2:
The protective layer is constructed as a composite structure with two different materials: a first protective layer comprising a first protective layer material and a second protective layer comprising a second protective layer material. This composite approach enables the protective layer to simultaneously provide optimal interface properties for both the photoelectric conversion layer and the support substrate, resolving the contradiction between manufacturing simplicity and dark current reduction.
2Reliability
If the protective layer is optimized for the photoelectric conversion layer interface, then the interface state at that interface is minimized, but the interface state at the support substrate interface increases, causing dark current
Solution Approach 1:
The patent implements local quality optimization by selecting specific protective layer materials for specific interfaces. The first protective layer material is chosen to minimize interface states at the photoelectric conversion layer interface, while the second protective layer material is chosen to minimize interface states at the support substrate interface. This localized optimization prevents dark current generation at both interfaces simultaneously.
Solution Approach 2:
The protective layer acts as an intermediary between the photoelectric conversion layer and the support substrate. By using different materials in the protective layer, the patent creates optimized intermediate interfaces that reduce interface states and prevent dark current, while still maintaining the structural connection between the photoelectric conversion layer and the support substrate.
3Reliability
If the protective layer is optimized for the support substrate interface, then the interface state at that interface is minimized, but the interface state at the photoelectric conversion layer interface increases, causing dark current
Solution Approach 1:
The patent applies local quality principles by differentiating the protective layer materials at different interfaces. The second protective layer material is optimized for the support substrate interface to minimize interface states, while the first protective layer material is optimized for the photoelectric conversion layer interface. This ensures both interfaces have minimal interface states and dark current is suppressed at both locations.
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
By selecting optimal protective layers for each surface, the imaging device effectively reduces interface states, minimizing dark current and preventing the deterioration of the light receiving element's characteristics.
Implementation Method 1
a photoelectric conversion layer that is provided on a first surface side of the support substrate and includes a second compound semiconductor
Data Source
AI summary
There is provided an imaging device that can suppress deterioration in characteristics. An imaging device includes: a support substrate that includes a first compound semiconductor; a photoelectric conversion layer that is provided on a first surface side of the support substrate and includes a second compound semiconductor having a composition different from a composition of the first compound semiconductor; a first protective layer that is provided in a trench penetrating the support substrate and the photoelectric conversion layer and is provided on a first side surface of the photoelectric conversion layer; and a second protective layer that is provided in the trench and is provided on a second side surface of the support substrate. The first protective layer and the second protective layer have different compositions. A first interface state generated between the first side surface and the first protective layer is smaller than an interface state generated between the first side surface and the second protective layer in a case where the second protective layer is in contact with the first side surface. A second interface state generated between the second side surface and the second protective layer is smaller than an interface state generated between the second side surface and the first protective layer in a case where the first protective layer is in contact with the second side surface.