Oxide TFT Layer Structure for Display Panel Mobility and Stability
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Solution Overview
Problem
The challenge is to ensure the stability of thin film transistors while improving their mobility in display panels, particularly as they evolve towards larger sizes and higher frame rates.
Innovation Solution
A display panel design incorporating a thin film transistor with a lower metal oxide layer made of indium oxide and lanthanoid oxide, and an upper metal oxide layer in a polycrystalline phase, connected to the source and drain electrodes, which enhances stability and mobility by reducing deep-level defects and oxygen vacancies, and provides corrosion resistance during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thin film transistor structure is used in display panels, then the display panel can achieve large sizes and high frame rates, but the stability and mobility of the thin film transistor become compromised
Solution Approach 1:
The metal oxide layer is segmented into two distinct layers: a lower metal oxide layer (amorphous or microcrystalline phase) that provides high mobility, and an upper metal oxide layer (polycrystalline phase) that provides high stability. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between mobility and stability.
Solution Approach 2:
Different regions of the metal oxide layer are assigned different crystal phases to achieve different local properties. The lower layer uses amorphous or microcrystalline phase for high carrier mobility, while the upper layer uses polycrystalline phase for high stability. This local differentiation allows the transistor to simultaneously achieve both high frame rate and stability.
2Reliability
If the metal oxide layer uses amorphous or microcrystalline phase to achieve high mobility, then the mobility of the thin film transistor is improved, but the stability deteriorates
Solution Approach 1:
The metal oxide layer is divided into two layers with different crystal phases. The lower layer uses amorphous or microcrystalline phase for high mobility, while the upper layer uses polycrystalline phase for high stability. This segmentation resolves the contradiction by assigning different phases to different functional requirements.
Solution Approach 2:
The metal oxide layer is constructed as a composite structure combining materials with different crystal phases. The lower layer (amorphous or microcrystalline) and upper layer (polycrystalline) work together to provide both high mobility and high stability, achieving properties that neither phase could provide alone.
3Ease of manufacture
If the upper metal oxide layer is etched to form source and drain electrodes, then the electrode structure is created, but the lower metal oxide layer may be damaged by corrosion
Solution Approach 1:
The upper metal oxide layer with polycrystalline phase is formed first as a protective barrier before the etching process. This preliminary protective layer prevents the etching solution from reaching and damaging the lower metal oxide layer, allowing easy electrode formation while protecting the underlying structure.
Solution Approach 2:
The upper metal oxide layer acts as an intermediary protective layer between the etching solution and the lower metal oxide layer. It withstands the corrosion of the etching solution, preventing direct contact with the lower layer and thus protecting it from damage during the electrode formation process.
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 achieves higher mobility and improved stability of the thin film transistor, ensuring better performance under various stress conditions, including gate bias and illumination stress.
Implementation Method 1
deep-level defects in the lower metal oxide layer and the upper metal oxide layer are reduced because of high breaking bond energy and low electronegativity of the lanthanide
Implementation Method 2
the lanthanoid inhibits oxygen vacancies to reduce concentration of the oxygen vacancies in the lower metal oxide layer
Implementation Method 3
The upper metal oxide layer includes the polycrystalline phase. The polycrystalline phase has better stability than amorphous phase or microcrystalline phase
Implementation Method 4
the polycrystalline phase in the upper metal oxide layer has good corrosion resistance to the etching solution. The upper metal oxide layer protects the lower metal oxide layer, thereby preventing the lower metal oxide layer from being damaged by corrosion
Data Source
AI summary
A display panel includes a gate electrode, a source electrode, a drain electrode, and a metal oxide layer disposed corresponding to the gate electrode. The metal oxide layer includes a lower metal oxide layer and an upper metal oxide layer stacked on the lower metal oxide layer. The lower metal oxide layer includes an indium oxide and a lanthanoid oxide. The upper metal oxide layer is located on a surface of the lower metal oxide layer adjacent to the source electrode and the drain electrode. The source electrode and the drain electrode are connected to the upper metal oxide layer. The upper metal oxide layer includes an indium oxide and a lanthanoid oxide, and the upper metal oxide layer includes polycrystalline phase.