TFT Active Layer Segmentation for Mobility and Aperture Ratio
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Solution Overview
Problem
The performance of TFTs using oxide semiconductor materials is degraded when exposed to external environments due to moisture or oxygen, leading to reduced mobility and adverse effects on display quality.
Innovation Solution
A TFT structure incorporating a first active layer with higher conductivity than the second active layer made of oxide semiconductor material, where the first active layer is positioned closer to the source and drain electrodes, or between two second active layers, with an etch stop layer to protect the second active layer from environmental exposure, enhancing electron transport speed and maintaining mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If oxide semiconductor material is used for the active layer, then the aperture ratio is improved and production cost is reduced, but the mobility is degraded when exposed to external environment
Solution Approach 1:
The active layer is segmented into multiple sub-layers: a first active layer made of oxide semiconductor material and a second active layer made of different material. This segmentation allows each layer to perform different functions - the first layer provides high aperture ratio while the second layer maintains mobility and protects against environmental degradation.
Solution Approach 2:
The invention uses a composite active layer structure combining oxide semiconductor material with other materials. The first active layer (oxide semiconductor) is combined with a second active layer (such as amorphous silicon or other conductive material) to create a composite structure that leverages the advantages of both materials while mitigating their individual disadvantages.
2Speed
If the first active layer with higher conductivity is positioned closer to source and drain electrodes, then electron transport speed is enhanced, but the complexity of layer arrangement increases
Solution Approach 1:
The invention applies local quality by positioning the first active layer (with higher conductivity) specifically closer to the source and drain electrodes where high current density exists, while the second active layer is positioned in the channel region. This localized optimization enhances electron transport speed at critical interfaces without requiring complete restructuring of the entire active layer.
Data Source
AI summary
A TFT is provided. The TFT includes an active layer, and the active layer includes a first active layer and a second active layer. The second active layer is made of the oxide semiconductor material, and the first active layer has conductivity greater than conductivity of the second active layer.