GOA TFT Active Layer Doping for Stable High-Mobility Display Panels
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Solution Overview
Problem
Conventional amorphous oxide semiconductors (AOS) TFTs face a trade-off between high mobility and high stability, particularly due to threshold voltage shifts under negative gate electrode bias stress and continuous light exposure, limiting their commercialization.
Innovation Solution
A display panel design incorporating a first active layer composed of indium zinc oxide doped with a lanthanide series element and scandium, along with a specific manufacturing process using a half-tone mask, to enhance stability without compromising mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cation doping or intentional oxygen supply methods are used to reduce oxygen vacancies, then stability is improved, but threshold voltage shift becomes too large to drive active matrix display
Solution Approach 1:
The patent changes the chemical composition parameters of the active layer by introducing specific dopants (铪 Hf, 钽 Ta, 锆 Zr from IVB group; 钪 Sc, 钇 Y from IIIB group) at controlled concentrations (0.1-5 at%). This parameter optimization reduces oxygen vacancies while maintaining threshold voltage within acceptable ranges, resolving the contradiction between stability improvement and threshold voltage control.
Solution Approach 2:
The patent creates a composite material system by combining indium zinc oxide base material with multiple dopant elements (IVB group + IIIB group). This composite approach leverages the synergistic effects of different dopants: IVB group elements reduce oxygen vacancies while IIIB group elements control carrier concentration, achieving both stability improvement and threshold voltage control simultaneously.
2Reliability
If zinc gallate (ZnGaO) is used to widen optical bandgap and improve NBTS stability, then stability is improved, but mobility is significantly reduced
Solution Approach 1:
Instead of using zinc gallate, the patent changes the material composition by using indium zinc oxide with controlled dopant additions. This parameter change maintains the optical bandgap properties needed for high mobility while achieving NBTS stability through oxygen vacancy reduction via IVB group dopants and carrier concentration control via IIIB group dopants.
Solution Approach 2:
The patent extracts the gallium element from the zinc gallate system that causes mobility degradation. By removing Ga and using alternative dopants (IVB and IIIB group elements), the patent achieves stability improvement without the harmful effect of disrupted electron transmission paths, thus maintaining high mobility.
3Speed
If high-mobility IZO TFTs are used, then mobility is improved, but carrier concentration and oxygen vacancies cannot be controlled, leading to negative threshold voltage shifts
Solution Approach 1:
The patent optimizes the compositional parameters by controlling dopant concentrations within specific ranges (0.1-5 at% for IVB group, 0.1-5 at% for IIIB group). This parameter control reduces oxygen vacancies and adjusts carrier concentration to maintain positive threshold voltage, while preserving the high mobility characteristics of IZO TFTs.
Solution Approach 2:
The patent applies different dopant functions at different local levels: IVB group dopants (Hf, Ta, Zr) are used locally to reduce oxygen vacancies, while IIIB group dopants (Sc, Y) are used locally to control carrier concentration. This localized quality control achieves threshold voltage stabilization without compromising the overall high mobility of the IZO material.
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 both high mobility and high stability in the thin-film transistor, addressing the trade-off issue by suppressing oxygen vacancies and maintaining lattice matching, while simplifying production processes and reducing costs.
Implementation Method 1
The solution achieves both high mobility and high stability in the thin-film transistor, addressing the trade-off issue by suppressing oxygen vacancies and maintaining lattice matching
Implementation Method 2
The solution achieves both high mobility and high stability in the thin-film transistor, addressing the trade-off issue by suppressing oxygen vacancies and maintaining lattice matching
Data Source
AI summary
The present invention relates to a display panel and its manufacturing method. The invention uses a lanthanide series element and scandium co-doped indium zinc oxide to prepare an oxide as the first active layer of the GOA region. The lanthanide series element suppresses the formation of excessive oxygen vacancies and serves as a conversion medium under blue light with low charge transfer transition energy. This greatly improves the stability of the thin-film transistor in the first active layer of the GOA region without affecting mobility. Scandium helps to suppress the formation of excessive oxygen vacancies, control carrier concentration, and maintain lattice matching, further enhancing the stability of the thin-film transistor in the GOA region.