Transparent Oxide TFT Structure for High-Aperture LCD Pixels
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Solution Overview
Problem
Current liquid crystal display devices face challenges in achieving high aperture ratio, low power consumption, and high-definition performance due to limitations in transistor design and materials used.
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 specific atomic ratio, to enhance light transmission and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If silicon semiconductors are used in transistors, then reliable switching function is achieved, but aperture ratio is reduced and power consumption increases
Solution Approach 1:
The patent changes the material parameter from silicon semiconductor to oxide semiconductor, which fundamentally alters the electrical and optical properties. Oxide semiconductors enable high aperture ratio because they can be made transparent in the visible range while maintaining semiconductor functionality, directly resolving the contradiction between aperture ratio and power consumption
Solution Approach 2:
The patent employs a stacked structure of multiple oxide semiconductor layers with different crystallinity states (amorphous, microcrystalline, and/or crystalline regions). This composite material approach allows optimization of both optical transparency and electrical properties, achieving high aperture ratio while maintaining reliable transistor operation and low power consumption
2Illumination intensity
If silicon semiconductors are used in transistors, then switching function is achieved, but light transmission is limited
Solution Approach 1:
The patent changes the material composition from silicon-based to oxide-based semiconductors, which fundamentally improves light transmission in the visible range. Oxide semiconductors have wider bandgap that allows visible light transmission while maintaining semiconductor properties, thus resolving the contradiction between light transmission and transistor reliability
Solution Approach 2:
The patent creates local quality variations within the oxide semiconductor layer by forming regions with different crystallinity (amorphous, microcrystalline, crystalline). This allows different regions to serve different functions: amorphous regions provide good light transmission, while crystalline regions provide reliable switching, together achieving both high light transmission and transistor reliability
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.