IGZO Composite Oxide Layer for Imaging Element Carrier Stagnation
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Solution Overview
Problem
The existing laminated imaging elements using IGZO semiconductor layers face carrier stagnation issues due to the large difference in state density between organic semiconductor materials and IGZO, affecting photoresponsiveness and charge transfer efficiency.
Innovation Solution
Incorporating a composite oxide layer with indium-gallium-zinc composite oxide, featuring a two-layer structure where the first layer has a higher indium, gallium, or zinc composition and lower oxygen content than the second layer, or higher carrier mobility, to improve charge transport and reduce recombination during charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor layer containing IGZO is used, then photoelectric conversion capability is achieved, but carrier stagnation occurs at the interface between the photoelectric conversion layer and the semiconductor layer due to large difference in state density
Solution Approach 1:
An intermediate layer is introduced between the photoelectric conversion layer and the IGZO semiconductor layer to serve as a mediator. This intermediate layer has state density that gradually transitions between the organic semiconductor material and IGZO, preventing carrier stagnation at the interface while maintaining photoelectric conversion capability.
Solution Approach 2:
The state density of the semiconductor layer is made non-uniform by creating a gradient structure where state density varies with position. The region adjacent to the photoelectric conversion layer has higher state density to match the organic material, while other regions maintain IGZO characteristics, thereby preventing carrier stagnation locally at the interface.
2Speed
If high-speed transfer of signal charges is required to avoid delay, then transfer speed must be increased, but this requires complex floating drain electrode structures
Solution Approach 1:
The floating drain electrode structure is removed from the device. Instead of using complex electrode arrangements for charge transfer, the invention relies on the optimized semiconductor layer properties and electric field control to achieve high-speed charge transfer without requiring floating drain electrodes.
Solution Approach 2:
The mechanical/electrical structure of floating drain electrodes is replaced with a field-based approach. By controlling the electric field through the semiconductor layer and using field effect to drive charge transfer, the invention achieves high-speed transfer without mechanical or complex electrical electrode structures.
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 photoresponsiveness by minimizing carrier stagnation and improving charge transfer efficiency, while preventing recombination and suppressing dark current generation.
Implementation Method 1
a photoelectric conversion layer formed on the semiconductor layer
Implementation Method 2
improve charge transport and reduce recombination during charge accumulation
Implementation Method 3
the first layer has a higher indium composition than the second layer... or the first layer has a higher carrier mobility than the second layer
Implementation Method 4
An imaging element using an organic semiconductor material for the photoelectric conversion layer can photoelectrically convert a specific color (wavelength band)
Data Source
AI summary
An imaging element (photoelectric conversion element) includes a photoelectric conversion unit formed by laminating a first electrode 21, a photoelectric conversion layer 23A, and a second electrode 22. Between the first electrode 21 and the photoelectric conversion layer 23A, a composite oxide layer 23B containing indium-gallium-zinc composite oxide is formed. The composite oxide layer 23B includes a first layer 23B1 adjacent to the first electrode 21 and a second layer 23B2 adjacent to the photoelectric conversion layer 23A. The first layer 23B1 has a higher indium composition than the second layer 23B2, or the first layer 23B1 has a higher gallium composition than the second layer 23B2, or the first layer 23B1 has a higher zinc composition than the second layer 23B2.