Oxide Semiconductor TFT Substrate for Luminance Consistency
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Solution Overview
Problem
The existing thin film transistor substrates face variations in carrier mobility due to heat treatment adjustments for amorphous silicon, leading to inconsistencies in luminance among pixels, as partial crystallization of silicon significantly alters mobility between amorphous and partially crystallized states.
Innovation Solution
A thin film transistor substrate design incorporating oxide semiconductors with different mobilities for switching and drive transistors, where the switching transistors and drive circuit transistors have higher mobilities than the light-emitting element transistors, allowing for precise mobility adjustment and reduced variations, using materials like InSiO and ZnON with varying nitrogen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat treatment is applied to adjust carrier mobility of amorphous silicon in pixels, then mobility can be adjusted to match pixel size requirements, but partial crystallization of silicon occurs causing significant mobility variations and luminance inconsistencies
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which fundamentally alters the mobility adjustment mechanism. Instead of relying on heat treatment that causes crystallization, the oxide semiconductor allows mobility control through composition ratios (e.g., In:Si:O ratios) and deposition conditions, achieving precise mobility adjustment without phase transition risks
Solution Approach 2:
The patent employs composite oxide semiconductor materials with specific element combinations (In-Si-O, Zn-O-N, etc.) to achieve desired mobility characteristics. By combining different elements in controlled ratios, the material provides both the required mobility range and structural stability, preventing the crystallization issues encountered with pure silicon
2Speed
If different semiconductor materials are used for drive circuit transistors and pixel transistors to meet different performance requirements, then high carrier mobility can be achieved in drive circuits, but mobility variations cause luminance variations among pixels
Solution Approach 1:
The patent applies local quality by using the same oxide semiconductor base material across all pixels but adjusting the composition ratio locally to match each pixel's specific requirements. This allows each pixel to have optimized mobility while maintaining material consistency, preventing luminance variations caused by material differences
Solution Approach 2:
The oxide semiconductor material serves multiple functions: it can provide high mobility for drive circuit transistors when needed, and can be adjusted to provide appropriate mobility for pixel transistors. This universal material platform eliminates the need for different semiconductor materials in different circuit regions, ensuring luminance uniformity while meeting diverse performance requirements
Data Source
AI summary
A display panel includes a substrate, a display element, a plurality of pixels arranged in a matrix, a drive circuit that drives the display element, a switching transistor in each of the plurality of pixels and selectively performs switching on the pixel that is to be caused to emit light, a first drive transistor in each of the plurality of pixels and drives a light-emitting element in the pixel, and a second drive transistor in the drive circuit. The switching transistor that is in each of the plurality of pixels, the first drive transistor that is in each of the plurality of pixels, and the second drive transistor in the drive circuit include oxide semiconductors. The switching transistor in each of the plurality of pixels and the second drive transistor in the drive circuit have a higher mobility than the first drive transistor in each of the plurality of pixels.