CNT N-Type Semiconductor Layering for Long-Term Air Stability
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Solution Overview
Problem
N-type semiconductor characteristics in CNT-FETs degrade over long-term storage under atmospheric conditions, and existing methods to prevent this often increase process complexity and result in partial degradation before achieving low oxygen permeability.
Innovation Solution
A bottom-gate, bottom-contact or bottom-gate, top-contact n-type semiconductor element structure is used, featuring a semiconductor layer with nanocarbon and a second insulating layer containing a compound with an ionization potential between 5.8 eV and 6.6 eV, along with a polymer, to stabilize n-type characteristics and maintain low oxygen permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a layer containing an organic compound with C-N bonds is formed on CNTs to achieve n-type semiconductor characteristics, then n-type characteristics are improved, but the characteristics degrade during long-term storage under atmospheric conditions
Solution Approach 1:
The patent uses a composite structure consisting of a semiconductor layer containing CNTs and an insulating layer containing electron-donating compounds. This composite material approach allows the system to achieve both n-type characteristics (through the electron-donating compound) and improved stability (through the protective insulating layer structure), resolving the contradiction between achieving n-type characteristics and maintaining long-term stability.
Solution Approach 2:
The insulating layer containing electron-donating compounds creates a protective environment around the CNTs, effectively isolating them from atmospheric oxygen and moisture. This inert environment approach prevents oxidation and degradation of the CNTs during long-term storage, thereby maintaining the n-type semiconductor characteristics without requiring vacuum or high-temperature processes.
2Reliability
If the oxygen permeability of the insulating layer is reduced to prevent degradation, then stability is improved, but the number of manufacturing processes increases
Solution Approach 1:
The patent combines multiple functions into a single insulating layer: it provides electrical insulation, donates electrons to create n-type characteristics, and acts as a barrier to oxygen and moisture. By merging these functions into one layer rather than requiring separate layers for each function, the patent reduces manufacturing complexity while achieving low oxygen permeability and stability.
Solution Approach 2:
The insulating layer containing electron-donating compounds serves multiple purposes simultaneously: it insulates the semiconductor layer, provides electrons to achieve n-type characteristics, and protects against atmospheric degradation. This multi-functional design eliminates the need for additional specialized layers, thereby reducing the number of manufacturing processes while maintaining stability.
3Manufacturing precision
If conventional vacuum and high-temperature processes are used for RFID tag manufacturing, then manufacturing precision is maintained, but manufacturing cost increases
Solution Approach 1:
The patent replaces mechanical/thermal processes (vacuum deposition, high-temperature annealing) with chemical/coating processes. The insulating layer containing electron-donating compounds can be deposited using low-temperature coating techniques, eliminating the need for expensive vacuum equipment and high-temperature furnaces while maintaining manufacturing precision through controlled chemical deposition.
Solution Approach 2:
The patent changes the processing parameters from high-temperature vacuum conditions to low-temperature atmospheric coating conditions. By using electron-donating compounds that can be deposited at low temperatures and do not require vacuum environments, the patent maintains semiconductor quality while dramatically reducing manufacturing costs and simplifying the production process.
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 provides improved n-type semiconductor characteristics and stability with a convenient manufacturing process, suitable for use in wireless communication devices and merchandise tags.
Implementation Method 1
a second insulating layer which contacts the semiconductor layer on a side opposite to the gate insulating layer with respect to the semiconductor layer; wherein the semiconductor layer contains carbon nanotubes, and the second insulating layer contains a compound with an ionization potential in vacuum of more than 5.8 eV and 6.6 eV or less
Implementation Method 2
the oxygen permeability of the second insulation layer is equal to or less than 4.0 cc/(m2·24h·atm)
Data Source
Figure 1~2
Figure 3A(a)~3A(e)
Figure 3B(f)~4
AI summary
An object of the present invention is to provide a n-type semiconductor element having improved n-type semiconductor characteristics and excellent stability with a convenient process. The n-type semiconductor element includes; a substrate; a source electrode, a drain electrode, and a gate electrode; a semiconductor layer in contact with the source electrode and the drain electrode; a gate insulating layer for insulating the semiconductor layer from the gate electrode; and a second insulating layer positioned on the opposite side of the semiconductor layer from the gate insulating layer and in contact with the semiconductor layer; in which, the semiconductor layer contains nanocarbon, and the second insulating layer contains (a) a compound with an ionization potential in vacuum of 7.0 eV or less, and (b) a polymer.