Oxide Semiconductor Pixel Transistors for Low-Leakage LCD Panels
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Solution Overview
Problem
Existing liquid crystal display devices using oxide semiconductors face challenges in achieving low power consumption and high image quality due to high off-current in transistors, leading to display deterioration and variability in outdoor environments.
Innovation Solution
The use of an oxide semiconductor with a wider band gap than silicon, combined with reduced impurity concentration, and metal nitride source and drain electrodes, results in a transistor with extremely low off-current, enabling stable signal holding and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxide semiconductor with lower electron carrier concentration is used, then transistor operation speed is improved, but on-off ratio becomes insufficient due to high off current
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor to oxide semiconductor, which fundamentally alters the electrical characteristics. By selecting oxide semiconductor with inherently lower electron carrier concentration, the patent achieves both high operation speed and low off current, resolving the contradiction between speed and on-off ratio through material parameter optimization
Solution Approach 2:
The patent employs a composite structure combining oxide semiconductor layer with metal nitride source and drain electrodes. This composite material system creates favorable interface characteristics that reduce off current while maintaining high electron mobility, thereby achieving both high speed operation and high on-off ratio
2Ease of manufacture
If conventional oxide semiconductor transistor is used, then manufacturing is simplified, but display deterioration occurs due to high off current
Solution Approach 1:
The patent modifies the semiconductor material parameter to oxide semiconductor, which maintains compatibility with existing thin film transistor manufacturing processes while fundamentally reducing off current. This parameter change enables simple manufacturing of transistors with excellent display quality stability
Solution Approach 2:
The patent uses oxide semiconductor that can be deposited using conventional sputtering equipment and processes, making the manufacturing approach cost-effective and compatible with existing production lines, thereby achieving reliable display quality without complex manufacturing
3Speed
If transistor with higher electron carrier concentration is used, then operation speed increases, but power consumption increases due to higher off current
Solution Approach 1:
The patent optimizes the electron carrier concentration parameter of the oxide semiconductor to a specific range that balances speed and power consumption. By controlling the oxide semiconductor properties, the patent achieves high switching speed while maintaining extremely low off current, thereby reducing power consumption
Solution Approach 2:
The combination of oxide semiconductor with metal nitride electrodes creates a composite structure that enhances electron mobility for fast switching while the oxide semiconductor's wide band gap ensures minimal leakage current, achieving both high speed and low power consumption simultaneously
4Use of energy by moving object
If oxide semiconductor transistor is used, then low power consumption is achieved, but image stability varies in outdoor environments
Solution Approach 1:
The patent uses a composite structure of oxide semiconductor with metal nitride source and drain electrodes. This composite material system provides stable electrical characteristics that are less sensitive to temperature variations and environmental conditions, ensuring image stability in outdoor environments while maintaining low power consumption
Solution Approach 2:
By optimizing the oxide semiconductor parameters and interface characteristics with metal nitride electrodes, the patent creates a transistor with stable electrical properties that maintain consistent performance across different temperatures and environmental conditions, resolving the image stability issue
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 approach significantly reduces off-current in transistors, maintaining image stability and quality even at varying temperatures and environments, while minimizing power consumption and display deterioration.
Implementation Method 1
use of an oxide semiconductor with a wider band gap than silicon
Data Source
AI summary
A display panel for displaying an image is provided with a plurality of pixels arranged in a matrix. Each pixel includes one or more units each including a plurality of subunits. Each subunit includes a transistor in which an oxide semiconductor layer which is provided so as to overlap a gate electrode with a gate insulating layer interposed therebetween, a pixel electrode which drives liquid crystal connected to a source or a drain of the transistor, a counter electrode which is provided so as to face the pixel electrode, and a liquid crystal layer provided between the pixel electrode and the counter electrode. In the display panel, a transistor whose off current is lower than 10 zA/μm at room temperature per micrometer of the channel width and off current of the transistor at 85° C. can be lower than 100 zA/μm per micrometer in the channel width.