OLED Thin Film Transistor Electrode Separation for Parasitic Capacitance
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Solution Overview
Problem
Oxide thin film transistors with an inverted staggered structure in OLED displays suffer from parasitic capacitance issues due to kick-back voltage, leading to potential defects and performance degradation.
Innovation Solution
The OLED display design includes a substrate with separated source and drain electrodes contacting the oxide semiconductor layer by a predetermined distance (more than 0 μm and no greater than 5 μm) to minimize parasitic capacitance, while maintaining effective charge mobility, using a configuration that includes two types of thin film transistors with overlapping and non-overlapping electrode structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If source and drain electrodes are separated from the gate electrode by a predetermined distance, then parasitic capacitance is minimized, but device area increases
Solution Approach 1:
The patent applies local quality by creating different spatial relationships between electrodes: in the first thin film transistor, source and drain electrodes contact the oxide semiconductor layer and are separated from the gate electrode to minimize parasitic capacitance; while in the additional thin film transistor, source and drain electrodes overlap the gate electrode to ensure effective charge mobility. This localized differentiation resolves the contradiction between minimizing parasitic capacitance and maintaining charge mobility within the same device structure.
Solution Approach 2:
The patent segments the thin film transistor structure into two distinct types: a first thin film transistor with separated electrodes for minimizing parasitic capacitance, and an additional thin film transistor with overlapping electrodes for ensuring charge mobility. This segmentation allows each transistor type to optimize for its specific function, resolving the contradiction between the two competing requirements.
2Reliability
If source and drain electrodes contact the oxide semiconductor layer, then charge mobility is maintained, but parasitic capacitance increases
Solution Approach 1:
The patent applies local quality by creating different spatial relationships between electrodes: in the first thin film transistor, source and drain electrodes contact the oxide semiconductor layer and are separated from the gate electrode to minimize parasitic capacitance; while in the additional thin film transistor, source and drain electrodes overlap the gate electrode to ensure effective charge mobility. This localized differentiation resolves the contradiction between minimizing parasitic capacitance and maintaining charge mobility within the same device structure.
Solution Approach 2:
The patent segments the thin film transistor structure into two distinct types: a first thin film transistor with separated electrodes for minimizing parasitic capacitance, and an additional thin film transistor with overlapping electrodes for ensuring charge mobility. This segmentation allows each transistor type to optimize for its specific function, resolving the contradiction between the two competing requirements.
Data Source
AI summary
An organic light emitting diode (OLED) display includes a substrate main body, a thin film transistor formed on the substrate main body, and an OLED formed on the substrate main body. The thin film transistor includes a gate electrode, an oxide semiconductor layer disposed on the gate electrode in an insulated manner, and source and drain electrodes respectively contacting the oxide semiconductor layer. Parts of the source and drain electrodes contacting the oxide semiconductor layer are separated from the gate electrode in a direction that is parallel with the substrate main body by a predetermined distance.