Thin Film Transistor Aperture Ratio and Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thin film transistors (TFTs) in flat display devices face challenges in achieving high aperture ratios and efficient power consumption due to parasitic capacitances and photo leakage currents, particularly when using oxide semiconductors that require crystallization processes or have uniformity issues.
Innovation Solution
A TFT design featuring a scan line, active layer with regions aligned along a direction, and insulating layers, where the active layer is formed using indium tin oxide (ITO) or indium zinc oxide (IZO), with a width larger than the scan line in a perpendicular direction, reducing overlapping areas and parasitic capacitances, and integrated capacitor electrodes to enhance the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the active layer width is increased to improve light transmission and aperture ratio, then the aperture ratio is improved, but the parasitic capacitance increases due to larger overlapping area with scan line
Solution Approach 1:
The active layer is divided into three distinct regions (first, second, and third regions) that are linearly and sequentially aligned along the first direction. This segmentation allows the active layer to extend beyond the scan line width in the second direction, increasing the aperture ratio while the segmented structure helps manage and reduce parasitic capacitance effects by distributing the electrical pathways.
2Reliability
If conventional oxide semiconductors are used that require crystallization processes, then the semiconductor properties are improved, but the manufacturing complexity and process difficulty increase
Solution Approach 1:
The patent changes the material parameter by using oxide semiconductors (such as ITO or IZO) that can function effectively in an amorphous state without requiring crystallization processes. This parameter change in material selection maintains good semiconductor properties while significantly simplifying the manufacturing process and eliminating the need for complex crystallization steps.
Data Source
AI summary
A thin film transistor (TFT) includes a scan line on a substrate, the scan line including a straight portion extending along a first direction, an active layer including an oxide semiconductor and overlapping the straight portion of the scan line, the active layer having a first region, a second region, and a third region that are linearly and sequentially aligned along the first direction, a first insulating layer between the active layer and the scan line, a first electrode connected to the first region of the active layer, and a second electrode connected to the third region of the active layer.