Stacked Oxide Thin-Film Transistor for Photostability and Mobility
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Solution Overview
Problem
Oxide semiconductor thin film transistors are prone to generating photogenerated carriers under light, affecting their stability, which is a challenge in large-sized high-resolution display applications.
Innovation Solution
A thin film transistor design featuring a stacked active layer with a crystalline oxide layer and a lanthanide oxide layer, where the indium atomic proportion varies and oxygen proportion increases away from the gate, and the lanthanide oxide layer captures photogenerated carriers to improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxide semiconductor thin film transistor is used, then high mobility and excellent uniformity are achieved, but photogenerated carriers are generated under light affecting stability
Solution Approach 1:
The active layer is divided into two distinct oxide layers: a first oxide layer (IGZO-based) providing high mobility and a second oxide layer (InOx-based) providing photostability. This segmentation allows each layer to specialize in one function, resolving the contradiction between mobility and stability.
Solution Approach 2:
The patent uses a composite structure of two different oxide materials with complementary properties. The IGZO-based material provides high electron mobility while the InOx-based material provides resistance to photogenerated carriers, creating a composite active layer that achieves both high mobility and excellent photostability.
2Speed
If indium atomic proportion is increased, then mobility is improved, but photogenerated carrier generation increases affecting stability
Solution Approach 1:
Different regions (layers) of the active layer have different compositional qualities optimized for different functions. The first oxide layer has higher indium content for mobility, while the second oxide layer has lower indium content and higher oxygen content for photostability, achieving local optimization of properties.
Solution Approach 2:
The patent systematically varies the atomic proportions of indium and oxygen between the two layers. The first oxide layer has higher indium atomic proportion for high mobility, while the second oxide layer has lower indium atomic proportion and higher oxygen atomic proportion to suppress photogenerated carrier generation, demonstrating parameter optimization to resolve the contradiction.
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
This design reduces defect states, decreases free carrier concentration, and enhances photostability by capturing photogenerated carriers, thereby improving the stability and mobility of the thin film transistor.
Implementation Method 1
the second oxide layer is a lanthanide oxide layer... the lanthanide oxide layer captures photogenerated carriers to improve stability
Data Source
AI summary
A thin film transistor includes a gate, a source, a drain, and an active layer. The active layer includes first and second oxide layers that are stacked, the source and the drain are both disposed at a side of the second oxide layer away from the first oxide layer, the first oxide layer is a crystalline oxide layer, and the second oxide layer is a lanthanide oxide layer. When the gate is disposed at a side of the first oxide layer away from the second oxide layer, an atomic proportion of an indium element in the first oxide layer is greater than that of the second oxide layer; when the gate is disposed at the side of the second oxide layer away from the first oxide layer, the atomic proportion of the indium element in the first oxide layer is less than that of the second oxide layer.