Rare-Earth Oxide Semiconductor for TFT Light Stability
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Solution Overview
Problem
Oxide semiconductor thin-film transistors face issues with stability due to oxygen vacancies and reduced electron mobility caused by doping, and exhibit poor light stability due to photo-induced carriers and holes.
Innovation Solution
Doping indium zinc oxide or indium gallium zinc oxide with a small amount of rare-earth oxides like praseodymium or ytterbium to suppress oxygen vacancies and create recombination centers for photo-induced carriers, enhancing mobility and light stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ga3+ ions are doped in large amounts to suppress oxygen vacancies, then stability is improved, but electron mobility is reduced due to dilution of In3+ concentration
Solution Approach 1:
The patent changes the doping parameter from conventional elements (Ga, Zn) to rare-earth elements (Pr, Yb), fundamentally altering the doping mechanism. This parameter change allows suppression of oxygen vacancies through a different physical mechanism (4f electron configuration of rare-earth elements) that does not rely on high doping concentrations, thereby maintaining high In3+ concentration and electron mobility while achieving stability
Solution Approach 2:
The patent introduces rare-earth elements with specific electron configurations (4f1 for Pr3+, 4f14 for Yb2+) that replicate the oxygen vacancy suppression function of conventional dopants but with superior efficiency at lower concentrations. The rare-earth elements copy the stabilizing effect while preserving the high mobility characteristics of undoped IGZO
2Stability of the object's composition
If Zn2+ ions are doped in large amounts to maintain amorphous structure, then uniformity is improved, but electron mobility is reduced due to dilution of In3+ concentration
Solution Approach 1:
The patent replaces Zn2+ doping with rare-earth element doping (Pr3+, Yb2+), changing the compositional parameter to achieve amorphous structure stabilization through a different mechanism. The rare-earth elements maintain the amorphous phase and uniformity without requiring high doping levels that would dilute In3+ concentration and reduce electron mobility
3Speed
If pure In2O3 is used to maintain high electron mobility, then speed is improved, but stability deteriorates due to abundant oxygen vacancies
Solution Approach 1:
The patent introduces rare-earth elements that copy the essential function of oxygen vacancy suppression while maintaining the high mobility characteristics of pure In2O3. The rare-earth dopants (Pr3+, Yb2+) provide the stabilizing effect against oxygen vacancies without the significant mobility reduction seen in conventional doping, effectively decoupling these two properties
4Stability of the object's composition
If IGZO material is used to achieve good uniformity, then homogeneity is improved, but light stability deteriorates due to photo-induced carriers and holes
Solution Approach 1:
The patent changes the compositional parameter by replacing conventional dopants (Ga, Zn) with rare-earth elements (Pr, Yb). This parameter change introduces recombination centers that actively manage photo-induced carriers through radiative and non-radiative recombination pathways, thereby improving light stability while maintaining the uniformity benefits of IGZO-based materials
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 approach results in high mobility and improved light stability of the semiconductor, maintaining high current switching ratios and weak photo-current characteristics, with optimal performance achieved at specific doping molar ratios of rare-earth oxides.
Implementation Method 1
a small amount of rare-earth oxide such as praseodymium oxide or ytterbium oxide is doped to suppress the oxygen vacancies effectively
Implementation Method 2
there are recombination centers for photo-induced carriers generated to enhance the light stability of the semiconductor
Implementation Method 3
the 5 s orbit of In3+ ions is the major electron transport orbit
Data Source
AI summary
The present application discloses a composite metal oxide semiconductor which is a metal oxide semiconductor doped with a rare earth oxide. Even doping the praseodymium oxide or ytterbium oxide at a small doping amount, oxygen vacancies could be suppressed as well as the mobility be maintained; critically, the thin-films made thereof can avoid the influence of light on I-V characteristics and stability, which results in great improvement of the stability under illumination of metal oxide semiconductor devices. The present application also disclose the thin-film transistors made thereof the composite metal oxide semiconductor and its application.