Oxide Semiconductor Driving Transistor Layout for Stable OLED Displays
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Solution Overview
Problem
The production of active matrix display devices is hindered by the complexity and cost associated with using polycrystalline silicon transistors, which require multiple photomasks and can result in varying crystallinity, affecting display quality, and oxide semiconductor transistors require precise carrier concentration control, complicating the device structure and increasing production complexity.
Innovation Solution
A display device structure featuring a driving transistor with an oxide semiconductor layer, dual gate electrodes, and transparent conductive layers, which simplifies the production process by reducing the number of photomasks needed and stabilizes the carrier concentration, allowing for a more efficient and productive manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polycrystalline silicon transistors are used, then display quality can be maintained, but production complexity increases due to multiple photomasks and varying crystallinity
Solution Approach 1:
The patent changes the material parameter from polycrystalline silicon to oxide semiconductor, which fundamentally alters the manufacturing requirements. Oxide semiconductors can be processed at lower temperatures and do not require multiple photomasks for crystallinity control, thus reducing production complexity while maintaining display quality through precise carrier concentration control achieved via the dual gate electrode structure
Solution Approach 2:
The transistor structure is segmented into dual gate electrodes (first and second gate electrodes) that independently control different aspects of carrier concentration. This segmentation allows precise control over threshold voltage and on-current characteristics without requiring complex single-step processing, thereby simplifying the overall production process
2Productivity
If dual gate electrodes are added, then on-current level and frequency characteristics improve, but device structure complexity increases
Solution Approach 1:
The dual gate electrode structure serves multiple functions simultaneously: the first gate electrode controls threshold voltage, the second gate electrode modulates on-current, and together they enable frequency characteristic optimization. This multi-functionality is achieved within a compact structure that does not significantly increase overall device footprint, balancing performance improvement with structural complexity
Data Source
AI summary
A display device includes a driving transistor and an organic EL element. The driving transistor includes an oxide semiconductor layer; a first gate electrode that includes a region overlapping the oxide semiconductor layer; a first insulating layer between the first gate electrode and the oxide semiconductor layer; a second gate electrode that includes a region overlapping the oxide semiconductor layer and the first gate electrode; a second insulating layer between the second gate electrode and the oxide semiconductor layer; and a first and a second transparent conductive layer that are provided between the oxide semiconductor layer and the first insulating layer and each include a region contacting the oxide semiconductor layer. The organic EL element includes a first electrode; a second electrode; a light emitting layer between the first electrode and the second electrode; and an electron transfer layer between the light emitting layer and the first electrode.