Polycrystalline Oxide Semiconductor Channel for Stable Display Operation
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Solution Overview
Problem
Conventional oxide semiconductors, such as IGZO, exhibit high mobility but are unsuitable for practical use due to significant light absorption issues, leading to erroneous operations like off-current increases when used in display devices, especially under illumination from backlights or organic EL devices.
Innovation Solution
A semiconductor device with a channel region made of an oxide semiconductor having a crystalline-to-non-crystalline volume ratio greater than 4, containing In, Zn, and optionally Ga or Al, and a thickness less than 300 nm, which is formed into a polycrystalline film to minimize visible light absorption and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If amorphous oxide semiconductor (e.g., IGZO) is used as the channel region material, then high carrier mobility (>10 cm²/V·s) is achieved, but significant light absorption occurs causing off-current increase and erroneous operation
Solution Approach 1:
The invention changes the structural parameter of the oxide semiconductor from amorphous to polycrystalline, specifically controlling the volume ratio of crystalline to non-crystalline components to be 1:4 or more. This parameter change reduces light absorption while maintaining high carrier mobility, resolving the contradiction between speed and reliability under illumination.
2Speed
If the oxide semiconductor layer thickness is increased, then higher carrier density and mobility are achieved, but light absorption increases causing dark current generation
Solution Approach 1:
The invention optimizes the thickness parameter of the oxide semiconductor layer to be 300 nm or less, and combines this with polycrystalline structure formation. This dual parameter optimization achieves high carrier mobility while suppressing light absorption-induced dark current, resolving the contradiction between speed and harmful factor generation.
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
The semiconductor device effectively suppresses dark current generation and maintains stable performance even under illumination, enabling high-quality displays with a large aperture ratio and lower power consumption, suitable for use in organic EL devices and other display types.
Implementation Method 1
even conventional oxide semiconductors are not entirely free of absorptions in the visible range and are associated with a problem that, for example, an erroneous operation such as an off-current increase is caused by carrier excitation due to slight light absorption
Data Source
AI summary
A semiconductor device includes a substrate and a semiconductor layer having a channel region, the channel region is made from an oxide semiconductor which satisfies Vc/Va>4 where Vc is a volume ratio of a crystalline component and Va is a volume ratio of a non-crystalline component.