Stacked Image Sensor Tunnel Oxide Film for Stable Charge Transfer
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Solution Overview
Problem
Oxide semiconductor layers in image pickup elements experience degradation due to oxygen loss, leading to fluctuating charge transfer characteristics and degraded image quality.
Innovation Solution
Incorporating an oxide film and oxide semiconductor layer below the photoelectric conversion layer, with specific energy level alignments and materials like metal oxides and tunnel oxide films, to stabilize the charge transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an oxide semiconductor layer is used in the image pickup element, then photoelectric conversion efficiency is improved, but oxygen loss occurs leading to fluctuating charge transfer characteristics
Solution Approach 1:
A tunnel oxide film is introduced as an intermediary layer between the photoelectric conversion layer and the oxide semiconductor layer. This tunnel oxide film acts as a mediator that prevents oxygen loss from the oxide semiconductor layer while maintaining efficient charge transfer, thus resolving the contradiction between photoelectric conversion efficiency and charge transfer stability
Solution Approach 2:
The tunnel oxide film creates an inert environment for the oxide semiconductor layer by isolating it from oxygen diffusion paths. This protective barrier prevents oxygen loss and maintains the stable characteristics of the oxide semiconductor layer, ensuring reliable charge transfer performance
2Speed
If high-speed charge transfer is required to prevent delay, then transfer speed is increased, but charge transfer efficiency deteriorates due to oxygen deficiency
Solution Approach 1:
The tunnel oxide film serves as a mediator that enables both high-speed and efficient charge transfer. It provides a controlled interface that maintains oxygen levels in the oxide semiconductor layer, ensuring that fast transfer does not compromise transfer efficiency
Solution Approach 2:
The energy level alignment parameters are optimized by introducing the tunnel oxide film with specific band structure. This parameter optimization allows the system to achieve both high transfer speed and high transfer efficiency by controlling the energy barriers at the interfaces
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 enhances charge storage and transfer efficiency, preventing oxygen deficiency and fluctuation in oxide semiconductor layer characteristics, resulting in improved image quality and reduced noise.
Implementation Method 1
a photoelectric conversion layer (light receiving layer) is sandwiched between two electrodes. The stacked image pickup element requires a structure for storing and transferring signal charge generated in the photoelectric conversion layer on the basis of photoelectric conversion.
Implementation Method 2
incorporating an oxide film and oxide semiconductor layer below the photoelectric conversion layer, with specific energy level alignments and materials like metal oxides and tunnel oxide films, to stabilize the charge transfer process
Data Source
AI summary
An image pickup element includes a photoelectric conversion section including a first electrode, a photoelectric conversion layer including an organic material, and a second electrode stacked on one another. Between the first electrode and the photoelectric conversion layer, an oxide semiconductor layer and an oxide film are formed from the first electrode side.