Photoelectric Conversion Element With Oxygen-Rich Work Function Layer
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Solution Overview
Problem
Existing solid-state imaging devices face limitations in further improving image quality, as previously proposed technologies have not effectively addressed the need for enhanced image capture capabilities.
Innovation Solution
A photoelectric conversion element is developed, comprising a first electrode, a work function control layer with a higher oxygen content than stoichiometric composition, a photoelectric conversion layer, an oxide semiconductor layer, and a second electrode, where the work function control layer contains hexavalent molybdenum or tungsten oxides, and optionally includes a p-type or n-type buffer layer and an auxiliary layer, to enhance charge transfer and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional work function control layer with stoichiometric composition is used, then the device structure is simple, but the image quality cannot be further improved
Solution Approach 1:
The patent applies parameter changes by modifying the oxygen content in the work function control layer from stoichiometric to non-stoichiometric (oxygen excess) composition. This changes the chemical state of the layer, creating oxygen vacancies that improve electron transfer efficiency and suppress dark current, thereby enhancing image quality without fundamentally changing the device structure
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Mo, W, V, Nb, Ta) in the work function control layer. This composite approach allows optimization of electronic properties through synergistic effects of different metals, improving charge accumulation and transfer while maintaining structural stability
2Speed
If the work function control layer contains oxygen-deficient composition, then electron transfer is enhanced, but dark current increases
Solution Approach 1:
The patent applies parameter changes by optimizing the oxygen content to be in excess rather than deficient. This counterintuitive approach creates a different type of non-stoichiometric composition that maintains oxygen vacancies for electron transfer while the overall oxygen excess stabilizes the structure and suppresses dark current generation
Solution Approach 2:
The patent uses composite materials containing multiple metal elements (Mo, W, V, Nb, Ta) in the work function control layer. This composite structure allows the material to simultaneously achieve high electron transfer speed through controlled oxygen vacancies while suppressing dark current through the stabilizing effect of multiple metal components
3Manufacturing precision
If a simple electrode structure is used, then the device is easier to manufacture, but charge accumulation cannot be completely depleted
Solution Approach 1:
The patent applies segmentation by dividing the electrode structure into multiple functional components: first electrode, second electrode, and third electrode (charge accumulation electrode). This segmentation allows each electrode to perform its specific function optimally, ensuring complete depletion of charge accumulation while maintaining manufacturability through standardized electrode fabrication processes
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 significantly improves image quality by suppressing dark current and hydrogen generation, ensuring stable operation of the oxide semiconductor layer and maintaining image quality without impairing the characteristics of the photoelectric conversion element.
Implementation Method 1
a work function control layer, wherein the work function control layer contains a larger amount of oxygen than an amount of oxygen satisfying a stoichiometric composition
Implementation Method 2
a photoelectric conversion layer
Implementation Method 3
an oxide semiconductor layer
Implementation Method 4
an electrode for charge accumulation that is placed apart from the second electrode and is placed facing the photoelectric conversion layer via an insulating layer
Data Source
AI summary
To provide a photoelectric conversion element that can improve image quality. Provided is a photoelectric conversion element including at least a first electrode, a work function control layer, a photoelectric conversion layer, an oxide semiconductor layer, and a second electrode in this order, and further including a third electrode, in which the third electrode is provided apart from the second electrode and is provided facing the photoelectric conversion layer via an insulating layer, and the work function control layer contains a larger amount of oxygen than an amount of oxygen satisfying a stoichiometric composition.