Multiple Charge Trap Layers for Display Afterimage Reduction
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Solution Overview
Problem
Display devices suffer from issues of reduced display quality, particularly in terms of afterimages and luminance, which are not adequately addressed by existing technologies.
Innovation Solution
A display device design incorporating multiple charge trap layers, including a first and second charge trap layer with specific oxygen and nitrogen-hydrogen bond ratios, thicknesses, and materials, along with a third charge trap layer formed under ammonia-free conditions, to enhance charge trapping and improve transistor performance and reduce afterimages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single charge trap layer is used, then the device structure is simple, but the afterimage reduction and luminance improvement are insufficient
Solution Approach 1:
The charge trap layer is divided into multiple sub-layers (first charge trap layer with silicon oxide and nitrogen, second charge trap layer with silicon oxide and oxygen, third charge trap layer with silicon nitride) positioned at different locations. Each sub-layer has specific composition ratios and thicknesses to target different aspects of charge trapping, thereby reducing afterimages more effectively than a single uniform layer while maintaining manageable structural complexity.
Solution Approach 2:
The charge trap structure employs composite materials with specific atomic ratios - the first charge trap layer contains silicon, oxygen, and nitrogen in controlled proportions; the second charge trap layer uses silicon oxide with specific oxygen content; the third charge trap layer uses silicon nitride. These composite material compositions are optimized to enhance charge trapping efficiency and reduce afterimages.
2Reliability
If the charge trap layer thickness is increased, then the charge trapping capacity improves, but the transistor threshold voltage control becomes difficult
Solution Approach 1:
Instead of using a single thick charge trap layer, the structure segments the total thickness into multiple thinner sub-layers (first charge trap layer: 50-200nm, second charge trap layer: 50-200nm, third charge trap layer: 50-200nm). This segmentation maintains adequate charge trapping capacity while improving controllability of the threshold voltage, as each thin sub-layer can be precisely controlled during fabrication.
Solution Approach 2:
Different sub-layers are positioned at different locations with specific local compositions - the first charge trap layer is positioned adjacent to the semiconductor layer with specific nitrogen content, the second charge trap layer is positioned at a different location with specific oxygen content, and the third charge trap layer is positioned accordingly with silicon nitride composition. This local quality differentiation optimizes charge trapping at each position while maintaining overall threshold voltage control.
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 reduces long-term afterimages and improves luminance by optimizing the charge trap layers' composition and structure, thereby enhancing overall display quality.
Implementation Method 1
a first charge trap layer disposed on the buffer layer and including silicon oxide, a second charge trap layer disposed on the first charge trap layer
Data Source
AI summary
A display device may include a first substrate, a first barrier layer disposed on the first substrate, a second substrate disposed on the first barrier layer, a second barrier layer disposed on the second substrate, a buffer layer disposed on the second barrier layer, a first charge trap layer disposed on the buffer layer and including silicon oxide, a second charge trap layer disposed on the first charge trap layer, the second charge trap layer including silicon oxide, and having an oxygen atom content smaller than an oxygen atom content of the first charge trap layer, a semiconductor layer disposed on the second charge trap layer and a light emitting element disposed on the semiconductor layer. The display device shows little afterimage and high luminance.