Segmented Imaging Element Structure for Complete Charge Depletion
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Solution Overview
Problem
The existing imaging elements face challenges in completely depleting the charge storage portion of the first photoelectric conversion unit, leading to increased kTC noise and deteriorated image quality, and there is a need for a configuration that simplifies and miniaturizes the structure in pixel regions with multiple imaging elements.
Innovation Solution
The proposed imaging element incorporates a photoelectric conversion unit with a charge storage electrode spaced apart from the first electrode via an insulating layer, featuring multiple segments of photoelectric conversion units, insulating layers, and charge storage electrodes, allowing for a charge transfer gradient that facilitates complete depletion and reliable charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If charges are stored directly in the floating diffusion layer without a charge storage electrode, then the structure is simpler, but the photoelectric conversion unit cannot be completely depleted leading to increased kTC noise and deteriorated image quality
Solution Approach 1:
A charge storage electrode is introduced as an intermediary component between the photoelectric conversion layer and the floating diffusion layer. This charge storage electrode completely depletes during photoelectric conversion, preventing kTC noise and ensuring high image quality, while maintaining a manageable structural complexity through its integration into the existing pixel architecture.
2Adaptability or versatility
If multiple imaging elements are arranged in pixel regions, then functional versatility is improved, but the structure becomes more complex and difficult to miniaturize
Solution Approach 1:
Multiple imaging elements are merged into a stacked configuration where first-type imaging elements (with organic photoelectric conversion layers) and second-type imaging elements (with inorganic photoelectric conversion layers) are vertically arranged. This merging approach enables functional versatility for capturing different wavelength bands while miniaturizing the overall pixel region structure by utilizing the vertical dimension rather than expanding horizontally.
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 configuration effectively suppresses kTC noise, improves image quality by ensuring complete charge depletion, and simplifies the pixel region structure, enabling efficient charge transfer and reducing afterimages and transfer residues.
Implementation Method 1
An imaging element using an organic semiconductor material for a photoelectric conversion layer can photoelectrically convert a specific color (wavelength band)
Data Source
AI summary
Provided is an imaging element including a photoelectric conversion unit formed by stacking a first electrode, a photoelectric conversion layer and a second electrode. The photoelectric conversion unit further includes a charge storage electrode which is disposed to be spaced apart from the first electrode and disposed opposite to the photoelectric conversion layer via an insulating layer. The photoelectric conversion unit is formed of N number of photoelectric conversion unit segments, and the same applies to the photoelectric conversion layer, the insulating layer and the charge storage electrode. An nth photoelectric conversion unit segment is formed of an nth charge storage electrode segment, an nth insulating layer segment and an nth photoelectric conversion layer segment. As n increases, the nth photoelectric conversion unit segment is located farther from the first electrode. A thickness of the insulating layer segment gradually changes from a first to Nth photoelectric conversion unit segment.