Oxide TFT LCD Pixel Structure for Higher Aperture Ratio
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Solution Overview
Problem
Conventional liquid crystal display devices face challenges in achieving high aperture ratio, low power consumption, and high definition while maintaining reliability, particularly due to the limitations of silicon semiconductor transistors in extracting light efficiently and managing power usage.
Innovation Solution
The use of a display device structure incorporating a transistor with a semiconductor layer comprising a stack of first and second metal oxide layers, where the first layer has lower crystallinity than the second layer, and including indium, aluminum, gallium, yttrium, or tin, with a c-axis aligned crystal part in the second layer, allowing for increased light transmission and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If silicon semiconductor transistors are used in liquid crystal display devices, then the transistor can provide sufficient switching performance, but the aperture ratio is reduced due to poor light transmission through the transistor structure
Solution Approach 1:
The patent changes the material parameter of the semiconductor layer from conventional silicon-based materials to oxide semiconductor materials (such as IGZO - indium gallium zinc oxide). This material substitution fundamentally alters the optical and electrical properties, enabling the transistor to transmit visible light while maintaining switching functionality. The oxide semiconductor material has a wider bandgap that allows visible light transmission unlike conventional silicon materials.
Solution Approach 2:
The patent employs composite material structures including stacked oxide semiconductor layers with different crystallinities, combined with specific electrode materials and insulating layers. The semiconductor layer itself may comprise multiple oxide semiconductor sub-layers with varying compositions and crystalline structures to optimize both optical transmission and electrical performance simultaneously.
2Illumination intensity
If the aperture ratio is increased to improve light extraction, then more light can pass through the display device, but power consumption increases due to reduced transistor efficiency
Solution Approach 1:
By changing to oxide semiconductor materials with superior field-effect mobility characteristics, the transistor can achieve the same switching performance with smaller dimensions. This allows the aperture ratio to be increased while the transistor remains efficient enough to maintain low power consumption through its improved electrical properties.
Solution Approach 2:
The patent segments the semiconductor layer into multiple oxide semiconductor sub-layers with different crystalline structures and compositions. This segmentation allows optimization of each layer's specific function - some layers provide high mobility for efficient switching, while others provide optimal optical transmission, achieving both high aperture ratio and low power consumption through layered functionality.
3Measurement precision
If conventional semiconductor materials are used, then the manufacturing process is well-established, but the definition and image quality are limited by the material's optical properties
Solution Approach 1:
The patent changes the semiconductor material parameter to oxide semiconductors that can be deposited at lower temperatures using techniques like sputtering. This enables high-definition displays with better light transmission while maintaining manufacturing feasibility through established thin-film deposition processes, achieving improved definition without excessive manufacturing complexity.
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 the aperture ratio, reduces power consumption, and achieves a high-definition display by optimizing light extraction and transistor reliability through the use of metal oxide layers with specific atomic ratios and crystallinity.
Implementation Method 1
The second metal oxide layer includes a c-axis aligned crystal part
Implementation Method 2
The pixel electrode, the common electrode, and the first region are each configured to transmit visible light. Visible light passes through the first region and the liquid crystal element and exits from the display device.
Data Source
AI summary
A display device includes a liquid crystal element, a transistor, a scan line, and a signal line. The liquid crystal element includes a pixel electrode, a liquid crystal layer, and a common electrode. The scan line and the signal line are each electrically connected to the transistor. The scan line and the signal line each include a metal layer. The transistor is electrically connected to the pixel electrode. A semiconductor layer of the transistor includes a stack of a first metal oxide layer and a second metal oxide layer. The first metal oxide layer includes a region with lower crystallinity than the second metal oxide layer. The transistor includes a first region connected to the pixel electrode. The pixel electrode, the common electrode, and the first region are each configured to transmit visible light. Visible light passes through the first region and the liquid crystal element and exits from the display device.