Oxide Semiconductor Transistor with Double-Layer Transparent Electrode
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Solution Overview
Problem
Existing liquid crystal display technologies face challenges with amorphous silicon thin film transistors (a-Si TFT) having low mobility and not satisfying constant current bias conditions, while polycrystalline silicon thin film transistors offer high mobility but are unsuitable for large-scale displays and require high-temperature processing.
Innovation Solution
A display apparatus utilizing an oxide semiconductor transistor with a base substrate, buffer layer, oxide semiconductor layer, gate insulating layer, gate electrode, and transparent electrodes with a double-layer structure, including a transparent metal layer and transparent conductive oxide, to achieve low contact resistance and stable channel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If amorphous silicon thin film transistor is used, then low-temperature process is achieved, but mobility is low and constant current bias condition is not satisfied
Solution Approach 1:
The patent changes the material parameter from conventional silicon to oxide semiconductor, which enables low-temperature processing while achieving high mobility and stable current characteristics. The oxide semiconductor layer is formed at low temperature but provides performance comparable to high-temperature polycrystalline silicon.
Solution Approach 2:
The patent uses a composite structure combining oxide semiconductor with specific electrode materials (such as ITO, IZO) and insulating layers. This composite approach optimizes both the low-temperature processing capability and the electrical performance, achieving low contact resistance and stable channel characteristics.
2Reliability
If polycrystalline silicon thin film transistor is used, then high mobility and constant current bias condition are satisfied, but high-temperature process is required and large-scale display suitability is reduced
Solution Approach 1:
The patent fundamentally changes the semiconductor material parameter from polycrystalline silicon to oxide semiconductor, which intrinsically allows low-temperature formation while maintaining high mobility. The oxide semiconductor can be deposited at low temperatures yet achieves carrier mobility sufficient for constant current bias operation.
Solution Approach 2:
The patent adopts oxide semiconductor which can be processed using simpler, lower-cost, low-temperature techniques compared to the complex high-temperature processes required for polycrystalline silicon. This makes large-scale display manufacturing more economically viable.
3Device complexity
If transparent electrode with single layer is used, then structure is simple, but contact resistance with oxide semiconductor is high
Solution Approach 1:
The patent employs a composite transparent electrode structure with multiple layers including ITO, IZO, or other transparent conductive oxide combinations. This multi-layer composite achieves low contact resistance with the oxide semiconductor channel while maintaining optical transparency and structural integrity.
Solution Approach 2:
The patent optimizes the electrode structure locally at the contact region with the oxide semiconductor, using specific material combinations and thicknesses in the transparent electrode layers to minimize contact resistance at this critical interface, while other portions of the electrode maintain transparency requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides satisfactory channel stability and low contact resistance, enabling efficient driving of pixels with reduced driving voltage and preventing hydrogen diffusion to the channel portion, thus maintaining transistor stability.
Implementation Method 1
preventing hydrogen diffusion to the channel portion, thus maintaining transistor stability
Data Source
AI summary
A display apparatus includes a base substrate and a buffer layer disposed on the base substrate. The display apparatus further includes an oxide semiconductor layer disposed on the buffer layer and including a source electrode, a drain electrode, and a channel portion. The display apparatus further includes a gate insulating layer disposed on the channel portion, a gate electrode disposed on the gate insulating layer, and a protective layer disposed on the gate electrode and the buffer layer and having a contact hole. The display apparatus further includes a transparent electrode overlapping a portion of the protective layer and electrically connected to one of the source electrode and the drain electrode through the contact hole. The transparent electrode includes a transparent metal layer and a transparent conductive oxide layer overlapping the transparent metal layer.