Metal Oxide HEM-TFTs for High Mobility and Low Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current thin film transistors for electronic displays and RF applications face limitations in achieving high charge carrier mobility and low series resistance, particularly due to the limitations of amorphous Si and Si-based technologies, which require extensive equipment and processes, and do not offer high switching speed or low power consumption.
Innovation Solution
The development of top gate and bottom gate single and double heterojunction high electron mobility thin film transistors (HEM-TFTs) using metal oxide, metal oxynitride, and metal nitride channel layers with spacer, doped, and barrier layers to enhance charge carrier mobility and reduce series resistance, while minimizing equipment and process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous Si layer is used as the channel, then the TFT can be manufactured with simple processes, but the electron mobility is limited to 2 cm2/V-sec or less
Solution Approach 1:
The patent changes the material parameter from amorphous Si to metal oxide semiconductors (such as In-Ga-Zn-O), fundamentally altering the electronic properties to achieve high electron mobility while maintaining compatibility with existing TFT manufacturing processes
Solution Approach 2:
The patent employs composite material structures including multiple metal oxide layers (channel layer, barrier layer, doped layer) with different compositions and functions, creating a heterostructure that optimizes both mobility and manufacturability
2Speed
If polycrystalline Si is used as the channel, then the electron mobility increases to about 100 cm2/V-sec, but more expensive equipment and substrates are required
Solution Approach 1:
The patent uses metal oxide semiconductors that can be deposited at low temperatures on flexible substrates, replacing the need for expensive high-temperature equipment and rigid substrates required for polycrystalline Si, thereby reducing device complexity and cost
Solution Approach 2:
The patent changes the deposition temperature parameter from high temperature (required for polycrystalline Si) to low temperature (below 200°C for metal oxides), enabling the use of simpler equipment and flexible substrates while achieving comparable or superior electron mobility
3Ease of manufacture
If traditional Si-based TFTs are used, then the manufacturing process is well-established, but the switching speed and power consumption performance are insufficient for RF applications
Solution Approach 1:
The patent changes the semiconductor material parameter from Si to metal oxides, achieving electron mobility greater than 100 cm2/V-sec (comparable to polycrystalline Si) while maintaining compatibility with existing TFT fabrication processes, thereby improving switching speed without sacrificing manufacturability
Solution Approach 2:
The metal oxide channel layer structure with barrier and doped layers is designed to self-optimize the charge carrier density and mobility through the heterostructure configuration, enabling high-speed switching performance inherent to the material system
Data Source
AI summary
Structures of high electron mobility thin film transistors (HEM-TFTs) are provided in this invention. In one embodiment, HEM-TFTs with a single heterojunction structure are disclosed to have a substrate, a first metal oxide channel layer, a first spacer layer, a first doped layer, a first barrier layer, a source, a drain and a gate. In another embodiment, HEM-TFTs with a double heterojunction structure are provided to have a substrate, a second barrier layer, a second doped layer, a second spacer layer, a first metal oxide channel layer, a second spacer layer, a second doped layer, a second barrier layer, a source, a drain and a gate. In yet another embodiment, HEM-TFTs with a single heterojunction structure are disclosed to comprise a substrate, a first metal oxynitride channel layer, a first spacer layer, a first doped layer, a first barrier layer, a source, a drain and a gate. In still another embodiment, HEM-TFTs with a double heterojunction structure are provided to include a substrate, a first barrier layer, a first doped layer, a first spacer layer, a first metal oxynitride channel layer, a second spacer layer, a second doped layer, a second barrier layer, a source, a drain and a gate.