Oxide TFT Active Layer Composition for Mobility and Leakage Control
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Solution Overview
Problem
Existing thin film transistors in flat panel displays, particularly oxide semiconductor TFTs, face challenges in optimizing electron mobility and reliability due to uniformity issues in the active layer composition.
Innovation Solution
The active layer of the transistor unit is designed with varying concentrations of gallium, zinc, and indium at different thickness locations, creating distinct regions with higher concentrations near the back channel to enhance electron mobility and reliability by controlling electron transmission and reducing scattering effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform concentration of metal elements is used in the active layer, then manufacturing process is simple, but electron mobility and transistor performance are insufficient
Solution Approach 1:
The active layer is designed with non-uniform metal element concentrations at different thickness locations. Specifically, the first metal element concentration at the first thickness location is higher than the second metal element concentration at the second thickness location, creating localized compositional variations that optimize electron mobility in different regions of the transistor channel.
Solution Approach 2:
The patent varies the concentration parameters of metal elements (first metal element and second metal element) at different thickness positions within the active layer. This parameter change approach allows optimization of electrical properties by controlling the ratio and distribution of metal elements throughout the active layer thickness.
2Reliability
If higher metal element concentration is used in the active layer, then electron mobility improves, but photo-leakage current increases
Solution Approach 1:
Different regions of the active layer have different metal element concentrations tailored to their specific functional requirements. The first thickness location has higher metal element concentration for enhanced electron mobility, while the second thickness location has lower concentration to minimize photo-leakage current, achieving spatial optimization of electrical properties.
Solution Approach 2:
The concentration ratio of first metal element to second metal element is varied at different thickness locations. This parameter optimization allows the active layer to achieve high electron mobility where needed while maintaining low photo-leakage current in other regions, resolving the trade-off between these two electrical properties.
Data Source
AI summary
A substrate module includes a first substrate and a transistor unit. The transistor unit is disposed on the first substrate, and the transistor unit includes an active layer, a first electrode, and a second electrode. The active layer has a first surface and a second surface, and the first surface is opposite to the second surface. The first electrode and the second electrode at least partially overlap the active layer. The second surface contacts the first electrode and the second electrode. The active layer has a first range and a second range, and the first range is closer to the second surface than the second range. A first gallium concentration and a first zinc concentration exist within the first range in the active layer, and the first zinc concentration is higher than the first gallium concentration.