Sn-Based P-Type Oxide TFT Channels With Low Off-Current
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Solution Overview
Problem
Existing p-type oxide semiconductors used in thin film transistors (TFTs) suffer from high defect densities and poor performance, particularly in complementary metal-oxide-semiconductor (CMOS) TFT circuits, limiting their effectiveness in display and electronic devices.
Innovation Solution
Development of Sn-based p-type oxide semiconductors, including ternary and higher order oxides with Sn (II) and additional metals, which are fabricated using atomic layer deposition (ALD) to form p-type TFTs with improved mobility and low off-current, suitable for CMOS TFT devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing p-type oxide semiconductors are used in TFTs, then device fabrication is simpler, but device performance is poor due to high defect densities
Solution Approach 1:
The patent changes the compositional parameters by incorporating multiple metal elements (In, Ga, Zn, Sn) in specific ratios to create a quaternary oxide semiconductor. This compositional optimization reduces defect densities and improves carrier mobility, achieving high performance while maintaining compatibility with existing TFT fabrication processes
Solution Approach 2:
The patent uses a composite quaternary oxide semiconductor material combining In, Ga, Zn, and Sn elements. This composite structure leverages the advantageous properties of each element: In for high mobility, Ga for wide bandgap, Zn for stability, and Sn for p-type conductivity, achieving superior overall performance
2Reliability
If ternary and higher order Sn-based p-type oxides are used, then mobility and off-current performance improve, but manufacturing process complexity increases
Solution Approach 1:
The patent merges multiple deposition steps into a single atomic layer deposition (ALD) process that simultaneously deposits multiple metal precursors. This integrated approach forms the quaternary oxide semiconductor in one continuous process, improving performance while avoiding the need for separate deposition and annealing steps required by conventional methods
3Reliability
If flexible TFTs with organic channels are used, then flexibility is achieved, but performance is insufficient compared to inorganic semiconductors
Solution Approach 1:
The patent changes the physical state parameters by forming an amorphous phase quaternary oxide semiconductor that can be deposited at low temperatures. This amorphous structure lacks grain boundaries and dislocations, providing high mobility comparable to crystalline materials while maintaining flexibility for bendable applications
Solution Approach 2:
The patent creates a composite structure combining the amorphous quaternary oxide semiconductor channel with flexible substrate and electrode layers. This composite device structure achieves both the high performance of inorganic semiconductors and the flexibility required for flexible displays and wearable electronics
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 Sn-based p-type oxide semiconductors provide high mobility and low off-current, reducing manufacturing costs and failures associated with separately packaged IC drivers, and enable flexible TFTs on flexible substrates with higher performance than organic channels.
Implementation Method 1
forming the Sn-based p-type oxide semiconductor layer involves an atomic layer deposition (ALD) process
Data Source
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AI summary
This disclosure provides p-type metal oxide semiconductor thin films that display good thin film transistor (TFT) characteristics. The p-type metal oxide thin films include ternary or higher order tin-based (Sn-based) p-type oxides such as Sn (II)-M-O oxides where M is a metal. In some implementations, M is a metal selected from the d block or the p block of the periodic table. The oxides disclosed herein exhibit p-type conduction and wide bandgaps. Also provided are TFTs including channels that include p-type oxide semiconductors, and methods of fabrication. In some implementations, the p-channel TFTs have low off-currents.