Oxide Layer Transistors for High-Resolution Display Driving Voltage
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Solution Overview
Problem
High-resolution display devices face challenges in achieving a wide range of driving voltages due to reduced driving current, which affects the performance and reliability of transistors in these devices.
Innovation Solution
Incorporating an oxide layer above the active layer in both driving and switching transistors, utilizing oxide semiconductors like indium, gallium, zinc, tin, and hafnium, to enhance device characteristics and reliability, and allowing for a wider range of driving voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to achieve high resolution, then the display resolution is improved, but the driving current of each pixel is reduced
Solution Approach 1:
The patent changes the material parameter of the semiconductor layer from conventional materials to oxide semiconductor (such as IGZO - indium gallium zinc oxide). This material substitution fundamentally alters the electrical characteristics, enabling ultra-low leakage current while maintaining high mobility, thus resolving the contradiction between high resolution (requiring many pixels) and sufficient driving current per pixel.
2Measurement precision
If the number of pixels is increased to achieve high resolution, then the display resolution is improved, but the driving voltage range is reduced
Solution Approach 1:
By changing the semiconductor material to oxide semiconductor, the patent achieves a broader threshold voltage range. The oxide semiconductor's unique properties allow for adjustable threshold voltages from negative to positive values, providing a wide driving voltage range that accommodates high-resolution displays with numerous pixels while maintaining adequate current drive capability.
3Speed
If the channel length is reduced to improve transistor performance, then the switching speed is improved, but the reliability is worsened due to increased leakage current
Solution Approach 1:
The patent changes the semiconductor material to oxide semiconductor, which inherently provides ultra-low leakage current (on the order of 10^-21 to 10^-24 A) even with short channel lengths. This material property allows aggressive scaling of channel length for high-speed switching while maintaining reliability through naturally suppressed leakage, unlike conventional semiconductors where short channels lead to significant leakage.
Data Source
AI summary
A display device includes pixels connected to scan lines and data lines intersecting the scan lines, wherein each of the pixels includes a light-emitting element, a driving transistor to control a driving current supplied to the light-emitting element according to a data voltage applied from the data lines, and a switching transistor to apply the data voltage of the data line to the driving transistor according to a scan signal applied from the scan lines. The driving transistor includes a first active layer having an oxide semiconductor and a first gate electrode below the first active layer. The switching transistor includes a second active layer having a same oxide semiconductor as the oxide semiconductor of the first active layer and a second gate electrode below the second active layer. At least one of the driving transistor and the switching transistor includes an oxide layer above each of the active layers.