Pixel Electrode Edge Curvature for Sensor Dark Current Reduction
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Solution Overview
Problem
Sensors with laminated structures face challenges in reducing dark current, which affects their sensitivity, particularly due to the geometry of pixel electrodes that can lead to increased electric field focus and dark current generation.
Innovation Solution
The design incorporates pixel electrodes with non-angulated upper edges, specifically with curvature radii between 1 nm to 50 nm, which reduce the electric field focus and dark current, improving sensitivity by minimizing the area where the electric field is concentrated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pixel electrodes have angulated upper edges, then manufacturing is simpler, but electric field focus increases and dark current increases
Solution Approach 1:
The patent applies curvature to the upper edges of pixel electrodes, transforming sharp angulated edges into rounded edges with controlled curvature radii (1-50 nm). This curvature modification reduces electric field concentration at the edges, thereby reducing dark current generation while maintaining manufacturing feasibility through standard photolithography processes
2Reliability
If curvature radius of pixel electrode edges is reduced, then dark current decreases and sensitivity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for edge curvature radii (1-50 nm, with preferred ranges of 1-20 nm or 5-10 nm) to optimize the balance between dark current reduction and manufacturing feasibility. These parameter specifications enable controlled curvature that reduces electric field focus while remaining compatible with standard semiconductor fabrication capabilities
3Productivity
If photoelectric conversion layer area overlapping with pixel electrodes is increased, then light conversion efficiency improves, but dark current increases due to larger electrode edge area
Solution Approach 1:
The patent applies different geometric characteristics to different regions of the pixel electrode structure. The upper edges are rounded with specific curvature radii to reduce dark current, while the main body area maintains sufficient photoelectric conversion layer overlap for efficient light conversion. This local differentiation allows simultaneous optimization of both light sensitivity and dark current reduction
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 design effectively reduces dark current and enhances sensor sensitivity by optimizing the curvature radius of pixel electrodes, as demonstrated through finite-difference time-domain simulations, leading to improved performance in light conversion and signal generation.
Implementation Method 1
a photoelectric conversion layer between the opposed electrode and the plurality of pixel electrodes. The photoelectric conversion layer may be configured to absorb light of at least one part in a wavelength spectrum and to convert the absorbed light into an electrical signal
Data Source
AI summary
A photoelectric conversion device may include one or more pixel electrodes and an opposed electrode and a photoelectric conversion layer between the one or more pixel electrodes and the opposed electrode. The photoelectric conversion layer may be configured to absorb light of at least one part in a wavelength spectrum and to convert the absorbed light into an electrical signal. Each pixel electrode has an upper surface facing the photoelectric conversion layer, a side surface, and a non-angulated edge where the upper surface and the side surface meet.