Oxide-Stack Transistors for High-Aperture Liquid Crystal Displays
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving high aperture ratio, low power consumption, and high definition while maintaining reliability, particularly due to the use of silicon semiconductors which absorb visible light and affect transistor performance.
Innovation Solution
Employing a transistor with a semiconductor layer comprising a stack of metal oxide layers, where one layer has lower crystallinity than the other, and using light-transmitting materials for the pixel electrode and scan lines, allowing visible light to pass through and reducing backlight intensity, thus increasing aperture ratio and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon semiconductors are used in transistors, then transistor performance is achieved, but visible light absorption increases and aperture ratio decreases
Solution Approach 1:
The patent changes the material parameter of the semiconductor from silicon-based to oxide semiconductor, which fundamentally alters the optical properties. Oxide semiconductors have different bandgap characteristics that reduce visible light absorption while maintaining transistor functionality, directly resolving the contradiction between transistor performance and aperture ratio
Solution Approach 2:
The patent employs a composite structure with multiple oxide semiconductor layers having different crystallinities. The first oxide semiconductor layer has lower crystallinity and the second has higher crystallinity, creating a composite material system that optimizes both electrical performance for transistor operation and optical transparency for high aperture ratio
2Illumination intensity
If higher backlight intensity is used, then display brightness is improved, but power consumption increases
Solution Approach 1:
The patent converts the previously harmful light absorption by silicon semiconductors into a beneficial feature by using oxide semiconductors with minimal light absorption. This allows the backlight to pass through more efficiently, achieving high display brightness with lower power consumption since less light energy is wasted as heat in the transistor layers
3Area of stationary object
If metal oxide layers with different crystallinity are stacked, then light transmission is improved and aperture ratio increases, but manufacturing complexity increases
Solution Approach 1:
The patent segments the oxide semiconductor layer into multiple sub-layers with different crystallinity levels. This segmentation allows each layer to be optimized for specific functions (light transmission vs. electrical performance) while maintaining overall manufacturability through a systematic layered structure that can be deposited using standard sputtering techniques
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.