KR20100002842A - Carbon nanotube transistor and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A carbon nanotube transistor and a manufacturing method thereof are provided to maintain the characteristics of an n-type semiconductor in air for long time by using a gadolinium as a source electrode and a drain electrode. CONSTITUTION: In a carbon nanotube transistor and a manufacturing method thereof, a source electrode(12) is formed on a substrate. A drain electrode(14) is formed on the substrate, and the carbon nanotube channel(18) interlinks the source electrode and the drain electrode. A part or greater of the drain electrode and source electrode is formed with a gadolinium metal. The carbon nanotube channel has the characteristics of n-type semiconductor chip.

Description

Carbon nanotube transistor and manufacturing method thereof

The present invention relates to a carbon nanotube transistor and a method of manufacturing the same. Specifically, the present invention relates to an n-type carbon nanotube transistor using a gadolinium (Gd) metal as a source electrode and a drain electrode, and a method of manufacturing the same.

Carbon Nanotube (CNT) is a carbon allotrope composed of carbon present on the earth in a large amount, and carbon is a substance in which a carbon is combined with other carbon atoms in a hexagonal honeycomb pattern to form a tube, and the diameter of the tube is nano It is a very small area of material at the metric level.

Carbon nanotubes are known to be the perfect new materials with almost no defects in existing materials, with excellent mechanical properties, electrical selectivity, excellent field emission characteristics, high efficiency hydrogen storage media, and are characterized by electrodischarge, pyrolysis, laser deposition, It is manufactured by advanced synthesis techniques such as plasma chemical vapor deposition, thermochemical vapor deposition, electrolysis, flame synthesis, and the like.

These carbon nanotubes are actually applied to almost all fields such as aerospace, biotechnology, environmental energy, materials industry, medicine, electronic computer, security and safety, etc. One of them is carbon nanotube transistor. .

The carbon nanotube transistor has a structure in which a channel region is formed of carbon nanotubes in a configuration consisting of a source electrode, a drain electrode, and a gate electrode. Carbon nanotubes constituting the channel region of the transistor have advantages of high electrical conductivity, high thermal conductivity, and good heat dissipation effect while exhibiting semiconductor or metal characteristics, and are also light and at least 100 times stronger than steel. It is very stable because it does not react well with the compound, which is very advantageous for the stable operation of the electronic device.

It is well known that carbon nanotube channels in such carbon nanotube transistors behave like p-type semiconductors in air. Specifically, the work function of the carbon nanotubes is about 4.3 to 4.8 eV, and the size of the band gap is about 0 to 2 eV in the case of general carbon nanotubes. However, for the construction of the carbon nanotube transistor, when the electrode metal is bonded to the carbon nanotube, charge transfer occurs at the metal / carbon nanotube interface. By the way, when the metal used for the electrode is commonly used Ti, Au, Cr, Pd, etc., the work function is about 5.5 eV, the balance band of the carbon nanotubes and the Fermi level of the metal for the electrode Since the holes in the balance band of the carbon nanotubes can be easily moved, the channel consisting of the carbon nanotubes acts as a p-type semiconductor in air. In addition, the hole doping effect by oxygen in the air also plays an important role in showing the p-type characteristics.

However, in order to develop various electronic devices and logic devices using semiconductors, development of not only p-type transistors but also n-type transistors is required.

Therefore, it is generally necessary to develop n-type transistors using carbon nanotubes having p-type characteristics, and two methodologies have been studied for this purpose.

Firstly, doping alkali metals such as K and Ca on carbon nanotubes, or increasing free electrons using polymers containing amines, etc.

Second, there is a method to exhibit n-type semiconductor characteristics by using a metal having a low work function to align the Fermi level of the metal in the conduction band of the carbon nanotubes.

In case of using the first methodology, alkali metals that induce electron doping are easily oxidized and not stable in air, so that the n-type semiconductor characteristic disappears after a certain time, and even in the second method, the work function is low. Since the metals are easily oxidized in the air to increase the work function, the carbon nanotube channel has a problem of recovering original p-type characteristics or exhibiting very low electrical conductivity.

Therefore, a method of manufacturing an n-type carbon nanotube transistor that maintains excellent characteristics for a long time in air is required for electronic device application of carbon nanotubes.

In order to solve the problems of the prior art as described above, the present invention is to provide an n-type carbon nanotube transistor not only excellent in electrical characteristics, but also does not show a change in long-term (more than three months) characteristics in the air.

In addition, the present invention is to provide a manufacturing method capable of easily manufacturing the n-type carbon nanotube transistor.

Carbon nanotube transistor according to an aspect of the present invention for solving the above problems is a substrate; A source electrode formed on the upper surface of the substrate; A drain electrode formed on the upper surface of the substrate; And a carbon nanotube channel connecting the source electrode and the drain electrode, wherein at least a portion of the source electrode and the drain electrode is made of a gadolinium metal. The carbon nanotube channel exhibits n-type semiconductor characteristics.

Here, the source electrode and the drain electrode may be made of a gadolinium metal having a thickness of 30nm or more.

The carbon nanotube channel may include one or more single-walled carbon nanotubes.

The source electrode and the drain electrode may be formed to contact the upper portions of both ends of the carbon nanotube channel.

In the carbon nanotube transistor, a gate electrode may be formed on a rear surface of the substrate.

The carbon nanotube channels are formed by thermal chemical vapor deposition, self-assembly from carbon nanotube solutions, inkjet printing, electrophoresis, or spin coating. In addition, the gadolinium metal is formed by e-beam deposition, sputter coating, or FIB.

According to another aspect of the present invention, there is provided a method of manufacturing a carbon nanotube transistor, comprising: a) forming the carbon nanotube channel on a substrate; b) forming a source electrode pattern and a drain electrode pattern respectively corresponding to the source electrode and the drain electrode at both ends of the carbon nanotube channel; And c) introducing a gadolinium metal to the source electrode pattern and the drain electrode pattern to a predetermined thickness or more to form a source electrode and a drain electrode.

In step b), the pattern formation of the source electrode and the drain electrode may be formed to include upper portions of both ends of the carbon nanotube channel.

In step c), the gadolinium metal may be introduced to a thickness of 30nm or more.

As described above, the carbon nanotube channel of the carbon nanotube transistor of the present invention uses gadolinium metal as the source electrode and the drain electrode, and has a thickness of 30 nm or more, so that the n-type semiconductor characteristics can be maintained in the air for a long time.

Accordingly, in the carbon nanotube transistor of the present invention, the electrode is made of gadolinium metal, and even though the electrode is oxidized in the air, the oxide film is present only on the surface, and thus a protective film for maintaining the n-type semiconductor characteristics against oxidation is unnecessary. The carbon nanotube transistor manufacturing method does not require a separate protective film manufacturing process. In addition, the carbon nanotube transistor manufacturing method of the present invention can use a conventional lithography process as it is, conventional carbon nanotube transistor manufacturing method.

Therefore, the carbon nanotube transistor manufacturing method of the present invention does not require a complicated manufacturing process and can mass-produce an n-type carbon nanotube transistor that is stable in air for a long time without a separate protective film or treatment for securing stability in the air. This is very significant in applications of carbon nanotube-based electronic devices.

The n-type carbon nanotube transistor of the present invention is a gadolinium metal having excellent wetting property with a low work function of 3.1 eV, such as a source electrode and a drain electrode, thereby achieving stability in air while showing excellent electrical properties. It was. Specifically, since the work function of the gadolinium metal is 3.1 eV, the conduction band and the Fermi level of the carbon nanotube channel having the work function of 4.3 to 4.8 eV coincide, so that the electrons of the conduction band move easily, and the main carrier is the electron. Therefore, the carbon nanotube channel has an n-type semiconductor characteristic.

As shown in FIG. 1, the n-type carbon nanotube transistor of the present invention includes a gadolinium source electrode 12, a gadolinium drain electrode 14, a gate electrode 16, and a carbon nanotube channel 18.

Specifically, the n-type carbon nanotube transistor of the present invention forms the gadolinium source electrode 12, the gadolinium drain electrode 14, and the carbon nanotube channel 18 on the substrate 10, the substrate 10 The gate electrode 16 is formed on the rear surface of the substrate.

Here, as the substrate 10, a SiO ₂ / Si substrate is preferably used.

Here, the carbon nanotube channel is preferably made of single-walled carbon nanotubes. More preferably, the single-walled carbon nanotube channel has a diameter of 0.5 to 2 nm and a length of 10 nm or more and 50 μm or less. Here, when the diameter of the carbon nanotube channel exceeds 2 nm, the bandgap of the carbon nanotube is relatively small, and even when bonded with the gadolinium metal electrode of the present invention, it exhibits ambipolarity to provide desired n-type semiconductor characteristics. May not be achieved.

 Here, the carbon nanotube channel may include only one single-walled carbon nanotube, or may include several carbon nanotubes. In this case, the carbon nanotube channel may include a carbon nanotube network.

The single-walled carbon nanotubes may be formed by directly growing on the substrate 10 by thermal chemical vapor deposition, but preferably, self-assembling the dispersed carbon nanotube solution, printing carbon nanotubes, or spin coating. Alternatively, it may be located on the substrate 10 by electrophoresis by electrophoresis.

In the present invention, the source electrode 12 and the drain electrode 14 are formed of a gadolinium metal, which may be formed by e-beam deposition, sputter coating, or focused ion beam (FIB). .

The gadolinium metal used in the present invention has a lower work function of 3.1 eV than Ti (work function: 4.8 eV) or Au (work function: 5.1 eV) commonly used as an electrode material. In addition, gadolinium metal has excellent bondability with carbon nanotubes, and has high wettability with respect to carbon nanotubes.

Also, unlike other rare earth metals, gadolinium metal is relatively stable in air, resistant to oxidation, and stable in air. Moreover, even when oxidation of the gadolinium metal proceeds, oxidation mainly proceeds on the surface to form an oxide film, thereby preventing oxidation of gadolinium therein.

In addition, gadolinium metal is conventionally used as an electrode material of an n-type transistor, but unlike the rare earth metal such as scandium (Sc), which is difficult to obtain and expensive, it has an advantage of being readily available and inexpensive.

In the present invention, the gadolinium source electrode 12, the gadolinium drain electrode 14 is configured to be in contact with the upper ends of the carbon nanotube channel 18, as shown in Figure 1, to maximize the contact surface of the electrode and the channel It is provided.

In the present invention, the gadolinium metal for the source electrode 12 and the drain electrode 14 is preferably formed to a thickness of 30 nm or more. Here, when the thickness of the metal of gadolinium is less than 30nm, gadolinium reacts with oxygen in the air to oxidize to increase the work function, so that the n-type semiconductor characteristics of the carbon nanotube channel cannot be maintained for a long time.

However, as in the present invention, when the thickness of the gadolinium metal is 30 nm or more, even if the outer gadolinium is oxidized, the oxidized gadolinium forms an oxide film to prevent further oxidation, so that the gadolinium metal in contact with the carbon nanotube channel is It will not oxidize. Accordingly, the n-type semiconductor characteristics of the carbon nanotube channel are maintained for a long time.

As described above, in the present invention, the source electrode 12 and the drain electrode 14 have a low work function of 3.1 eV and use a gadolinium metal having excellent wettability with carbon nanotubes as an electrode material, thus making the source electrode manufactured. (12) and the Fermi level of the drain electrode 14 are aligned so as to be parallel to the electron band of the carbon nanotube channel 18, so that the carbon nanotube channel 18 has n-type semiconductor characteristics.

As described above, the present invention imparts excellent n-type semiconductor characteristics to the carbon nanotube channel 18 by using gadolinium having a low work function as the source electrode 12 and the drain electrode 14, and the source electrode 12, And the thickness of the gadolinium deposited for the formation of the drain electrode 14 is 30 nm or more, thereby making the n-type semiconductor characteristic of the carbon nanotube channel 18 stable for a long time.

The n-type carbon nanotube transistors of the present invention have stable n-type semiconductor characteristics for a long time, and thus, there is no need for a separate protective film formation method or a protective film treatment method, and may be manufactured by applying the existing carbon nanotube semiconductor manufacturing process as it is. .

Such an n-type carbon nanotube transistor of the present invention comprises the steps of 1) forming a carbon nanotube as a channel at a desired position on a substrate, and 2) respectively corresponding to a source electrode and a drain electrode at both ends of the carbon nanotube channel. Forming a source electrode pad and a drain electrode pattern so as to form a source electrode and a drain electrode by introducing gadolinium in a predetermined thickness or more into the source electrode pattern and the drain electrode pattern to remove unwanted portions of gadolinium; It can be prepared through a step.

The n-type carbon nanotube transistor manufacturing method of the present invention will be described in detail.

First, the formation of the single-walled carbon nanotube channel of step 1) may be performed using various methods such as direct growth, self-assembly, inkjet printing, spin coating, or electrophoresis.

In addition, the pattern formation of the source electrode and the drain electrode of step 2) is preferably formed to include the upper ends of both ends of the carbon nanotube channel.

The pattern of the source electrode and the drain electrode may be formed by a method of patterning an electrode shape using a lithography technique such as photolithography or e-beam lithography.

In addition, the gadolinium electrode formation of step 3) may be performed by forming gadolinium metal in the formed pattern region by e-beam deposition or sputter coating.

More specifically, first, in order to fabricate a carbon nanotube transistor, a photoresist is laminated on a silicon substrate insulated with a SiO ₂ layer, and a mask corresponding to the carbon nanotube channel is placed over the photoresist layer. In addition, the light is irradiated to remove the denatured photosensitive material exposed to light with an etching solution to form a pattern corresponding to the channel. At this time, the photosensitive material is not particularly limited, but preferably polymethyl methacrylate (hereinafter, referred to as 'PMMA') is used.

Thereafter, a liquid catalyst is introduced to form carbon nanotubes in the thus produced pattern. Although the Fe / Mo catalyst solution was used as the liquid catalyst in the present embodiment, any one that can promote growth of carbon nanotubes is used without particular limitation. Preferably, transition metals such as Co, Fe, Ni, Mo, or Cu, proteins containing transition metals such as ferritin, other reagents containing iron ions (FeCl ₃ , FeSO ₄ ), Dendrimers containing iron ions, or gold nanoparticles may be used as catalysts for the growth of carbon nanotubes.

Then, after soaking the silicon substrate is grown by the reaction with a liquid catalyst the carbon nanotubes formed in the acetone solution, removal of all of the photosensitive material layer made of PMMA, the catalyst-treated silicon substrate at a CH _4, 900 ℃ in H ₂ atmosphere It is grown in a furnace for 10 minutes to form single-walled carbon nanotubes in the channel.

As another method for forming single-walled carbon nanotube channels, a carbon nanotube solution prepared by laser ablation or arc discharge is dispersed on a substrate on which coordinate systems have been previously formed using electron beam lithography. Thereafter, the position of each carbon nanotube channel may be determined using AFM and the like, and an electrode may be generated using electron beam lithography at the determined position to manufacture a carbon nanotube device.

Another method for the formation of single-walled carbon nanotube channels is to form a self-assembled layer on the substrate and then react with the carbon nanotube dispersion in the solution to position the carbon nanotubes in the desired position on the substrate. Can be.

As another method for forming single-walled carbon nanotube channels, the inkjet printing technique may be used to form carbon nanotube channels by applying carbon nanotube ink at desired positions.

As another method for forming a single-walled carbon nanotube channel, a source electrode and a drain electrode are fabricated in advance, and then a carbon nanotube channel is pulled toward the electrode by applying AC power to a solution containing carbon nanotubes. Can be formed.

Alternatively, carbon nanotube channels can be made by spin coating a solution containing carbon nanotubes onto a substrate and then patterning and etching.

Thereafter, a source electrode and a drain electrode are formed of gadolinium metal on both ends of the thus formed carbon nanotube channel, thereby manufacturing a transistor as shown in FIG. 1.

The gadolinium source electrode and drain electrode forming method is to form a source electrode and a drain electrode pattern including the upper ends of the carbon nanotube channel using photolithography or e-beam lithography, respectively, and a source electrode pattern and drain formed using an e-beam evaporator. After depositing and forming gadolinium on the electrode pattern, hot acetone or a remover is used to selectively remove the gadolinium metal film of unwanted portions other than the source electrode and the drain electrode.

Hereinafter, the present invention will be described in more detail with reference to the following examples and experimental examples, but the protection scope of the present invention is not limited to the following examples.

Example

SiO ₂ / Si substrates were prepared, PMMA was stacked and portions corresponding to the channels of the transistors were patterned and removed. After the Fe / Mo catalyst solution was applied to the patterned channel, the PMMA layer was lifted off.

The SiO ₂ / Si substrate coated with the Fe / Mo catalyst solution on the corresponding channel portion was introduced into a furnace of CH ₄ , H ₂ atmosphere, and then heated to 900 ° C. for 10 minutes to grow carbon in the corresponding channel portion. The channel was formed of single-walled carbon nanotubes.

After forming the source electrode pattern and the drain electrode pattern on the substrate on both sides of the carbon nanotube channel formed as described above through photolithography, the source electrode pattern and the drain electrode pattern are not broken by using e-beam evaporation. 50 nm of gadolinium was deposited inside to form a source electrode and a drain electrode.

Thereafter, the gadolinium metal deposited on the undesired site was removed by dipping in an acetone solution to form a carbon nanotube transistor device having a length of 5 mm and a carbon nanotube having a diameter of 1.2 nm.

Experimental Example 1

The carbon nanotube transistor device manufactured according to the embodiment is positioned in a vacuum and atmospheric state, respectively, and 60, 120, 180, 240, and 300mv are applied to the source electrode and the drain electrode of the carbon nanotube transistor device as bias voltages, respectively. In addition, the change of the electrical characteristics was observed while changing the gate voltage from -10V to 10V.

Accordingly, as can be seen in Figure 2, the carbon nanotube transistor produced by the embodiment exhibited excellent semiconductor characteristics that the strength of the current increases above a certain voltage (threshold voltage).

Specifically, the carbon nanotube transistor fabricated in Example showed n-type semiconductor characteristics in air and had excellent charge mobility (mobility) of 811 cm ² / Vs.

로 유도되게 되는데, 이때 탄소나노튜브채널의 길이 L=5㎛, 탄소나노튜브의 직경 r=1.2 nm, 산화막의 두께 500 nm를 식에 대입하면 커패시턴스 Cg=3.31×10^-11F/m 가 되고, 전하이동도

는 바이어스 300 mV 에서 dI / dV _g = 0.175 μS를 대입하여 수득하였다. This charge mobility shows that when modeling a carbon nanotube transistor as a cylinder on a plate, the capacitance

When the length of the carbon nanotube channel L = 5㎛, the diameter of the carbon nanotube r = 1.2 nm, and the oxide thickness of 500 nm are substituted into the equation, the capacitance Cg = 3.31 × 10 ^-11 F / m becomes , Charge mobility

DI / dV at 300 mV bias Obtained by substitution of _g = 0.175 μS.

In addition, the Ion / Ioff ratio of the carbon nanotube transistor was 10 ⁵ or more, which showed excellent n-type semiconductor characteristics. Here, it can be seen that Ion / Ioff ratio is 5 × 10 ⁵ from Ion of 0.926 μA and Ioff of 1.6 pA at 300 mV.

Such excellent transistor device characteristics are thought to be because gadolinium not only has a low work function, but also gadolinium forms an excellent bond with carbon nanotubes as can be seen in the electronic structure calculation results of FIGS. 6A and 6B. Aluminum also has a low work function of 4.1 eV. However, as shown in FIG. 6B, the semiconductor properties are not as good as the carbon nanotube transistors according to the exemplary embodiment of the present invention because of poor coupling with carbon nanotubes.

Experimental Example 2

Next, the electrical characteristics of the transistors with time change were observed.

The electrical characteristics in the air / vacuum of the carbon nanotube transistor device manufactured according to the embodiment were measured by dividing 1 day after the device fabrication and after 55 days, respectively, in the same manner as in Experimental Example 1.

As can be seen in Figure 3, even after 55 days, the carbon nanotube transistor bonded with a gadolinium metal was found to exhibit excellent n-type transistor characteristics. In addition, it was confirmed that the semiconductor characteristics in the vacuum and the semiconductor characteristics in the air were almost the same after the 55 days.

 Experimental Example 3

Next, the experiment was performed while controlling the thickness of the gadolinium metal by varying the deposition time to determine the effect of the change in the gadolinium metal thickness.

Thus, the electrical properties of the carbon nanotube transistor device manufactured in various thicknesses according to the embodiment was measured in the same manner as in Experiment 1.

As shown in FIG. 4, when the thickness of the source electrode and the drain electrode is 10 nm, it can be seen that the electrical conductivity of the device has already decreased significantly after 3 days, and after 10 days or more, the resistance increases infinitely and measured. No more electrical conductivity was observed as this became impossible.

On the other hand, when the thicknesses of the source electrode and the drain electrode are 10 nm or more and less than 30 nm, for example, 20 nm, as shown in FIG. 5, the semiconductor characteristics become low over time. Specifically, FIG. 5A shows that after 0 days, FIG. 5B shows after 15 days, and FIG. 5C shows after 25 days, which shows that the semiconductor characteristics deteriorate significantly with time.

Therefore, it can be seen that the stability in air greatly depends on the thickness of the gadolinium metal of the source electrode and the drain electrode.

In order to more clearly see the effect of the gadolinium metal thickness of the source electrode and the drain electrode, a p-type carbon nanotube transistor in which a Ti / Au metal is bonded to the electrode to show the p-type semiconductor characteristics as shown in Figure 7a, Here, gadolinium nanoparticles were deposited and their effects were observed.

As shown in FIG. 7B, the device operates as an n-type semiconductor after deposition of gadolinium nanoparticles, but again recovers p-type characteristics in air as shown in FIG. 6C. It is thought that the gadolinium particles adsorbed on the carbon nanotubes exhibit p-type characteristics as they are completely oxidized.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the technical idea of the present invention, and it is obvious that the present invention belongs to the appended claims. Do.

1 is a conceptual diagram of a carbon nanotube transistor device.

FIG. 2 is a graph showing a change in drain current with respect to gate voltage application in the carbon nanotube transistor device of the present invention.

3 is a graph showing the change of the drain current with respect to the gate voltage applied after a predetermined time in the carbon nanotube transistor device of the present invention.

4 is a graph showing a change in stability of a carbon nanotube transistor according to the thickness of the gadolinium metal.

5 shows a change in characteristics of a carbon nanotube transistor over time.

6A is an electronic structure showing the bonding property between a gadolinium metal and carbon nanotubes.

6B is an electronic structure showing the bonding between aluminum metal and carbon nanotubes.

7A is a graph showing electrical characteristics of a p-type carbon nanotube transistor.

FIG. 7B is a graph showing electrical characteristics after the deposition of gadolinium metal on the carbon nanotube transistor of FIG. 7A.

FIG. 7C is a graph showing the electrical characteristics of the carbon nanotube transistor of FIG. 7B after a certain time.

Claims (11)

Board; A source electrode formed on the upper surface of the substrate; A drain electrode formed on the upper surface of the substrate; And A carbon nanotube channel connecting the source electrode and the drain electrode; Including, Carbon nanotube transistor, characterized in that at least a portion of the source electrode and drain electrode made of a gadolinium metal. The method of claim 1, And the carbon nanotube channel exhibits n-type semiconductor characteristics. The method of claim 1, The carbon nanotube transistor, wherein the source electrode and the drain electrode are made of a gadolinium metal having a thickness of 30 nm or more. The method of claim 1, The carbon nanotube transistor of claim 1, wherein the carbon nanotube channel comprises at least one single-walled carbon nanotube. The method of claim 1, And the source electrode and the drain electrode are in contact with upper portions of both ends of the carbon nanotube channel. The method of claim 1, And the gate electrode is formed on the rear surface of the substrate. The method according to any one of claims 1 to 6, And the carbon nanotube channel is formed by thermal chemical vapor deposition, self-assembly from a carbon nanotube solution, inkjet printing, electrophoresis, or spin coating. The method according to any one of claims 1 to 6, And the gadolinium metal is formed by e-beam deposition, sputter coating, or FIB. In the method for producing a carbon nanotube transistor is formed between the source electrode and the drain electrode, the gate electrode is formed on one side of the carbon nanotube channel, a) forming the carbon nanotube channel on a substrate; b) forming a source electrode pattern and a drain electrode pattern respectively corresponding to the source electrode and the drain electrode at both ends of the carbon nanotube channel; And c) forming a source electrode and a drain electrode by introducing a gadolinium metal in a predetermined thickness or more into the source electrode pattern and the drain electrode pattern; Carbon nanotube transistor manufacturing method comprising a. The method of claim 9, In step b), The pattern formation of the source electrode and the drain electrode is formed to include an upper portion of both ends of the carbon nanotube channel. The method of claim 9, In step c), The gadolinium metal is a carbon nanotube transistor manufacturing method, characterized in that introduced to a thickness of 30nm or more.

Images