Infrared Light Receiving Element With Pixel Light-Shielding Electrode
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Solution Overview
Problem
Infrared sensors using compound semiconductor light receiving elements face challenges in improving sensitivity due to light leakage and color mixture between pixels, especially when a light-shielding film is not disposed between pixels.
Innovation Solution
A light receiving element with a first electrode layer having light-shielding properties is provided between pixels on the light incident surface side, eliminating the need for a transparent electrode, and a stacked structure with an insulating layer and transparent electrode layer is used over the photoelectric converter to reduce the thickness of the contact layer, enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transparent electrode layer is provided over the photoelectric conversion layer to improve sensitivity, then light transmission is enhanced, but light leakage and color mixture between adjacent pixels occur
Solution Approach 1:
The patent divides the electrode structure into multiple segments: a light-shielding film disposed between adjacent pixels to block light leakage, and transparent electrode portions extending over the pixels to maintain light transmission. This segmentation allows each portion to perform its specific function without interfering with the other, resolving the contradiction between sensitivity and light leakage prevention.
Solution Approach 2:
The patent applies different properties to different regions of the electrode structure. The region between pixels uses a light-shielding material with high light-blocking capability, while the region over the pixels uses a transparent material with high light transmission. This local differentiation of properties allows the structure to simultaneously prevent light leakage in critical areas while maintaining light transmission in functional areas.
2Object-affected harmful factors
If a light-shielding film is disposed between pixels to prevent light leakage, then color mixture is reduced, but sensitivity and light transmission deteriorate
Solution Approach 1:
The electrode structure is segmented into light-shielding portions between pixels and transparent portions over pixels. This segmentation ensures that light shielding is applied only where necessary to prevent color mixture, while light transmission is maintained where required for sensitivity, thus resolving the contradiction between preventing color mixture and maintaining sensitivity.
Solution Approach 2:
Different optical properties are assigned to different spatial locations: light-shielding characteristics are localized to the regions between pixels to prevent color mixture, while transparent characteristics are localized to the regions over pixels to maintain sensitivity. This spatial differentiation resolves the contradiction by applying the right property in the right location.
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 reduces light leakage and color mixture, improving the sensitivity of the infrared sensor by providing a light-shielding property between pixels and optimizing the contact layer thickness, thereby enhancing the sensor's performance.
Implementation Method 1
a first electrode layer that is provided between the plurality of pixels on light incident surface side of the photoelectric converter, and has a light-shielding property
Implementation Method 2
a photoelectric converter that is provided as a layer common to the plurality of pixels, and contains a compound semiconductor material
Data Source
Figure 1
Figure 2~2(C)
Figure 3A~3B
AI summary
A first light receiving element according to an embodiment of the present disclosure includes a plurality of pixels, a photoelectric converter that is provided as a layer common to the plurality of pixels, and contains a compound semiconductor material, and a first electrode layer that is provided between the plurality of pixels on light incident surface side of the photoelectric converter, and has a light-shielding property.