Display Device Recessed Substrate Transistor Channel Length
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Solution Overview
Problem
Display devices with light emitting diodes face challenges in increasing the driving range of transistors and capacitance of storage capacitors, which are essential for improved luminance and stable light emission, due to limited area allocation per pixel as resolution increases.
Innovation Solution
The display device incorporates a substrate with recess portions that allow for semiconductor and electrode structures with protrusions and depressions, increasing the channel length of driving transistors and the area of storage capacitors, thereby enhancing their performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the display device is increased, then the display quality is improved, but the area allocated to each pixel is reduced
Solution Approach 1:
The patent introduces a third dimension by forming recess portions in the substrate and creating protrusions in the semiconductor layer and electrode structures that extend into these recesses. This vertical dimensionality allows the transistor channel length and capacitor area to be increased without expanding the planar pixel area, thereby maintaining high resolution while improving device performance.
2Ease of operation
If the channel length of the driving transistor is increased, then the driving range is improved, but the area occupied by the transistor is increased
Solution Approach 1:
The semiconductor layer is formed with protrusions that extend into the recess portions of the substrate, allowing the channel length to be increased in the vertical direction rather than the planar direction. This enables a longer channel length for improved driving range while occupying the same or reduced planar area.
Solution Approach 2:
The protrusions of the semiconductor layer are nested within the recess portions of the substrate, creating a nested structure that increases the effective channel length without proportionally increasing the overall device area. The electrode structures similarly nest within the recesses to increase capacitor area.
3Reliability
If the area of the storage capacitor is increased, then the capacitance is improved, but the area occupied by the capacitor is increased
Solution Approach 1:
The electrode structures of the storage capacitor are formed with protrusions that extend into the recess portions of the substrate, increasing the effective capacitor area in the vertical dimension. This allows for higher capacitance values without requiring additional planar area, as the capacitance is proportional to the electrode surface area.
Data Source
AI summary
A display device includes a substrate including a first recess portion, a semiconductor layer that overlaps the first recess portion, the semiconductor layer including protrusions and depressions conforming to a shape of the first recess portion, and a gate electrode that overlaps the first recess portion and the semiconductor layer, the gate electrode including protrusions and depressions conforming to the shape of the first recess portion. A thickness of the substrate in the first recess portion is less than a thickness of the substrate in a non-recess portion, excluding the first recess portion.