Amorphous Oxide TFT with Segmented Oxygen-Gradient Semiconductor
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Solution Overview
Problem
Amorphous silicon TFTs have low mobility and poor stability, making them unsuitable for large-area AMOLED displays, while polysilicon TFTs require high-temperature processes or have poor uniformity, and amorphous oxide TFTs face issues with threshold voltage and parasitic resistance, limiting their current driving capacity.
Innovation Solution
An amorphous oxide thin film transistor with a semiconductor active layer comprising a channel layer with a higher oxygen content than the ohmic contact layer, where the channel layer contacts the gate insulating layer and the ohmic contact layer has two separated regions contacting the source and drain electrodes, formed using sputtering in oxygen-contained and non-oxygen atmospheres respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous oxide is used to form the semiconductor channel with low carrier concentration and high resistance, then the threshold voltage control is improved, but the parasitic resistance of source and drain electrodes is increased, reducing current driving capacity
Solution Approach 1:
The semiconductor active layer is segmented into two distinct layers: a channel layer with high oxygen content for threshold voltage control, and an ohmic contact layer with low oxygen content for reducing parasitic resistance. This segmentation allows each layer to optimize its function independently.
Solution Approach 2:
Different regions of the semiconductor active layer have different oxygen contents tailored to their specific functions: the channel layer has high oxygen content (30-70 at%) for electrical stability and threshold voltage control, while the ohmic contact layer has low oxygen content (0-10 at%) for low resistance contact with electrodes.
2Reliability
If amorphous oxide TFTs are used for large-area AMOLED displays, then high carrier mobility and excellent uniformity are achieved, but threshold voltage instability and parasitic resistance issues limit current driving capacity
Solution Approach 1:
The semiconductor active layer is divided into channel layer and ohmic contact layer with distinct oxygen contents, allowing the channel layer to maintain excellent uniformity while the ohmic contact layer minimizes parasitic resistance at electrode interfaces.
Solution Approach 2:
The oxygen content parameter is changed spatially within the semiconductor active layer: high oxygen content (30-70 at%) in the channel layer for stability and uniformity, and low oxygen content (0-10 at%) in the ohmic contact layer for low resistance, thus resolving the contradiction between uniformity and parasitic resistance.
3Device complexity
If a single-layer semiconductor active layer is used, then the structure is simple, but both threshold voltage control and parasitic resistance reduction cannot be optimized simultaneously
Solution Approach 1:
The semiconductor active layer is segmented into two functional layers with different oxygen contents, enabling simultaneous optimization of threshold voltage control and parasitic resistance reduction while maintaining relatively simple overall device structure.
Solution Approach 2:
The semiconductor active layer is formed as a composite structure with two layers having different oxygen compositions, allowing each layer to contribute its optimal properties: the channel layer provides threshold voltage control while the ohmic contact layer provides low resistance contact.
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 configuration improves the current driving capacity by reducing parasitic resistance and enhancing stability, allowing for effective use in large-area AMOLED displays with improved uniformity and threshold voltage control.
Implementation Method 1
formed using sputtering in oxygen-contained and non-oxygen atmospheres respectively
Data Source
AI summary
Embodiments of the disclosed technology provide an amorphous oxide thin film transistor (TFT), a method for preparing an amorphous oxide TFT, and a display panel. The amorphous oxide thin film transistor includes: a gate electrode, a gate insulating layer, a semiconductor active layer, a source electrode and a drain electrode. The semiconductor active layer comprises a channel layer and an ohmic contact layer, and the channel layer has a greater content of oxygen than the ohmic contact layer; the channel layer contacts the gate insulating layer, and the ohmic contact layer comprises two separated ohmic contact regions, one of which contacts the source electrode and the other of which contacts the drain electrode.