CNT Thin Film Transistor Protrusion Alignment
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Solution Overview
Problem
Existing carbon nanotube thin film transistors have unordered carbon nanotube distributions, leading to high node resistance and low on-state current and carrier mobility due to the metallic nature of carbon nanotubes, limiting their performance.
Innovation Solution
The carbon nanotube thin film transistor design includes a channel region with protrusions that constrain carbon nanotube distribution to be substantially parallel to the source-drain direction, reducing node resistance and improving carrier mobility by aligning carbon nanotubes along the length direction between the source and drain electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon nanotubes are used as transistor channel material, then electrical properties are improved, but metallic nature causes limited application range due to poor current on-off ratios
Solution Approach 1:
The patent segments the carbon nanotube population by separating metallic and semi-conducting nanotubes through solution processing. This segmentation allows selective removal of metallic nanotubes that cause poor on-off ratios, while retaining semi-conducting nanotubes that provide good electrical properties and switching characteristics.
Solution Approach 2:
The patent extracts harmful metallic nanotubes from the carbon nanotube mixture through solution separation and purification processes. This extraction eliminates the negative impact of metallic nanotubes on current on-off ratios while preserving the beneficial semi-conducting nanotubes.
2Reliability
If mesh-like carbon nanotube thin film transistors are manufactured, then current on-off ratios are improved, but unordered distribution causes large node resistance and low carrier mobility
Solution Approach 1:
The patent applies preliminary action by pre-aligning carbon nanotubes in a specific orientation before forming the final transistor structure. This preliminary alignment ensures that nanotubes are oriented favorably for charge transport, reducing node resistance and improving carrier mobility before the device is completed.
Solution Approach 2:
The patent transitions from two-dimensional random mesh distribution to three-dimensional oriented arrangement by controlling nanotube alignment during deposition. This dimensional change allows nanotubes to be positioned with specific orientations that minimize scattering and reduce node resistance while maintaining the mesh-like structure for good on-off ratios.
3Ease of manufacture
If unordered carbon nanotube distribution is used, then manufacturing is simplified, but large number of nodes causes high resistance and low performance
Solution Approach 1:
The patent changes the orientation parameter of carbon nanotubes from random to aligned while maintaining the solution-based manufacturing approach. This parameter change reduces the number of nodes and their resistance without significantly complicating the manufacturing process, as the alignment is achieved through controlled deposition conditions rather than complex post-processing.
Data Source
AI summary
The present disclosure provides a carbon nanotube thin film transistor (CNT-TFT) and its manufacturing method. The carbon nanotube thin film transistor includes a source electrode, a drain electrode, a channel region, a plurality of protrusions, and a carbon nanotube layer. The channel region is between the source electrode and the drain electrode. The plurality of protrusions are at, and extend in a length direction of, the channel region. The carbon nanotube layer is disposed over the plurality of protrusions, and comprises a plurality of carbon nanotubes.