Carbon Nanotube Thin Film Transistor Heterojunction Alignment

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Solution Overview

Problem

Conventional thin film transistors using carbon nanotubes face issues with non-uniform dispersion, impurities, low carrier mobility, and inflexibility due to aggregation and the difficulty in eliminating organic solvents, limiting their application.

Innovation Solution

A thin film transistor design featuring a semiconducting layer composed of successively oriented carbon nanotube segments joined by Van der Waals attractive forces, aligned from the source to the drain electrode, which are integrated into a flexible substrate to enhance carrier mobility and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If carbon nanotubes are printed as a mixture with polymer on substrate, then the semiconducting layer can be formed, but the carbon nanotubes aggregate and cannot be uniformly dispersed

Engineering Contradiction:
Improveuniformity of carbon nanotube dispersionVSAvoidfabrication process complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention divides the carbon nanotube structure into segments of 5-membered rings and 7-membered rings within the graphene sheet, creating heterojunctions that prevent aggregation and enable uniform dispersion while maintaining semiconducting properties

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the structural parameters of carbon nanotubes by introducing defects (5-membered and 7-membered rings) during growth, transforming them from uniform structures to heterojunction structures with controlled semiconducting behavior and improved dispersion

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If organic solvent is used in carbon nanotube layer, then the carbon nanotubes can be processed, but impurities remain difficult to eliminate

Engineering Contradiction:
Improvepurity of carbon nanotube layerVSAvoidsolvent elimination difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates organic solvents from the carbon nanotube layer through controlled processing, removing impurities while preserving the semiconducting properties and structural integrity of the carbon nanotube heterojunctions

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses strong oxidizing conditions to treat the carbon nanotube layer, accelerating the removal of organic solvent residues and impurities through oxidation, thereby achieving high purity without compromising the carbon nanotube structure

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

3Reliability

If conventional carbon nanotube structure is used, then the transistor can be fabricated, but carrier mobility is low

Engineering Contradiction:
Improvecarrier mobilityVSAvoidnanotube structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention introduces local structural variations (5-membered and 7-membered rings) at specific positions within the carbon nanotube graphene sheet, creating heterojunctions with tailored electronic properties that enhance carrier mobility while maintaining overall structural feasibility

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention creates composite carbon nanotube structures combining metallic and semiconducting regions with heterojunctions, forming a composite material system that leverages the advantages of both regions to achieve high carrier mobility in the semiconducting channel

Inventive Principle:
Principle #40Composite materials

4Length of moving object

If carbon nanotubes are aligned side-by-side by CVD method, then the array can be formed, but the length is limited to about 100 microns

Engineering Contradiction:
Improvecarbon nanotube lengthVSAvoidalignment uniformity
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The invention performs preliminary alignment of carbon nanotubes during the CVD growth process itself, establishing the desired orientation and spacing before the nanotubes reach their final length, enabling both long length and uniform alignment to be achieved simultaneously

Inventive Principle:
Principle #10Preliminary action

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 solution achieves high carrier mobility and flexibility, overcoming the limitations of previous carbon nanotube-based transistors by ensuring uniform alignment and eliminating impurities, resulting in improved performance and application potential.

Implementation Method 1

comprises a plurality of successively oriented carbon nanotube segments joined end-to-end by Van der Waals attractive force therebetween

Methodology Applied
Scientific EffectVan der Waals force: Van der Waals Force

Data Source

PatentEP2120274B1Carbon Nanotube Thin Film Transistor
Publication Date: 2018.01.03 HON HAI PRECISION INDUSTRY CO LTD
  • EP2120274B1 patent drawingFigure 1
  • EP2120274B1 patent drawingFigure 2
  • EP2120274B1 patent drawingFigure 3

AI summary

A thin film transistor includes a source electrode, a drain electrode, a semiconducting layer, and a gate electrode. The drain electrode is spaced from the source electrode. The semiconducting layer is connected to the source electrode and the drain electrode. The gate electrode is insulated from the source electrode, the drain electrode, and the semiconducting layer by an insulating layer. The semiconducting layer includes a carbon nanotube layer. And the carbon nanotube layer includes a plurality of semiconducting carbon nanotubes. The at least part of the plurality of semiconducting carbon nanotubes are oriented along a direction from the source electrode to the drain electrode. The present disclosure further discloses a thin film transistor panel using the above described thin film transistor.