Selenium Photoelectric Conversion Element with In-Ga-Zn Oxide Blocking Layer
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Solution Overview
Problem
High-resolution imaging devices, such as those for 8K resolution, face challenges with reduced pixel area leading to decreased light-receiving areas in photoelectric conversion elements, resulting in low sensitivity under low illuminance conditions and high dark current, which affects imaging quality and fabrication yield due to issues with gallium oxide particle contamination and low crystallinity.
Innovation Solution
A photoelectric conversion element with a selenium-based photoelectric conversion layer and an In-Ga-Zn oxide hole injection blocking layer with a CAAC structure is used, which reduces dark current and improves adhesion and crystallinity, enhancing imaging performance under low illuminance and maintaining high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the area of a pixel is reduced to achieve high integration, then the number of pixels per unit area increases, but the light-receiving area of the photoelectric conversion element decreases, resulting in decreased sensitivity to light
Solution Approach 1:
The invention changes the material parameter of the photoelectric conversion layer from conventional materials to selenium, which has a higher absorption coefficient. This allows the photoelectric conversion layer to be made thinner while maintaining or improving light sensitivity, thus resolving the contradiction between high pixel integration and light-receiving area.
2Reliability
If a photoelectric conversion element utilizing avalanche charge multiplication is used to improve sensitivity under low illuminance, then sensitivity increases, but dark current increases, causing deterioration in imaging quality
Solution Approach 1:
The invention changes the material parameter to selenium, which inherently provides gain through its photoelectric conversion characteristics without requiring high electric fields. This achieves sensitivity improvement under low illuminance while avoiding the dark current problem associated with avalanche multiplication.
3Object-generated harmful factors
If a hole injection blocking layer formed using gallium oxide is stacked over the photoelectric conversion layer to reduce dark current, then dark current decreases, but particle contamination occurs and crystallinity is low, affecting fabrication yield
Solution Approach 1:
The invention changes the material parameter from gallium oxide to an In-Ga-Zn-O compound, which forms a crystalline structure. This eliminates particle contamination during deposition and achieves both dark current reduction and high fabrication yield through improved material crystallinity and deposition characteristics.
Solution Approach 2:
The invention uses a composite In-Ga-Zn-O compound material that combines the benefits of gallium oxide (dark current reduction) with additional elements (indium and zinc) that improve crystallinity and reduce particle contamination. This composite material approach resolves both the dark current and manufacturing precision issues.
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 enables excellent imaging performance, low power consumption, high-speed operation, and high reliability with reduced pixel variations, suitable for wide temperature ranges and high-resolution applications.
Implementation Method 1
a first layer which contains selenium and functions as a photoelectric conversion layer
Implementation Method 2
a second layer which contains In, Ga, Zn, and O and functions as a hole injection blocking layer
Data Source
AI summary
A photoelectric conversion element includes a first electrode, a second electrode, a first layer, and a second layer. The first layer is provided between the first electrode and the second electrode. The second layer is provided between the first layer and the second electrode. The first layer contains selenium. The second layer contains In, Ga, Zn, and O. The second layer may contain an In—Ga—Zn oxide. The selenium may be crystalline selenium. The first layer functions as a photoelectric conversion layer. The second layer functions as a hole injection blocking layer. The In—Ga—Zn oxide may have a c-axis aligned crystal.