KR20120097295A - Method for producing nanowire having acid and alkali - Google Patents

Abstract

PURPOSE: A manufacturing method of nano-wires which are stable under an acid anaerobic condition is provided to prevent the nano-wires from being dissolved in acid and basic solution, and blood. CONSTITUTION: A manufacturing method of nano-wires which are stable under an acid anaerobic condition comprises the following steps: growing the nano-wire on top of a substrate; and forming a protective layer with hydrocarbon or carbon fluoride on the nano-wire surface by using plasma. The nano-wire in the first step is composed of the one selected from ZnO, SnO2, and Si and GaN. The second step comprises the following steps: and forming a protective layer with hydrocarbon or carbon fluoride on top of the nano-wire surface by using the plasma. In the second step, the plasma vapor deposition condition is electricity of 100-1000W, the pressure of 10-100mTorr, and the flow rate of 10-100sccm of providing gas.

Description

Method for producing nanowires that are stable in acid and basic atmospheres

The present invention relates to a method for producing nanowires capable of producing stable nanowires, such as insoluble in acid and basic solutions.

Nanowires nanometers in diameter (1 nm = 10 ^-9 m) is the area, hundreds of length much greater than the diameter of nanometers, micrometers (1 ㎛ = 10 ^-6 m) or greater millimeter (1mm = 10 ^- Linear material with units of ³ m). The physical properties of these nanowires depend on their diameter and length.

The nanowires may be applied to a variety of micro devices due to their small size, and may have an advantage of using optical characteristics indicating movement characteristics or polarization of electrons in a specific direction.

The fabrication of such nanowire devices can be classified into two types according to the approach. One is to use a conventional semiconductor process, particularly an ultra-fine photolithography process, to etch a material such as silicon to directly insert a nanowire device at a desired position. Bottom-up to fabricate nanowire devices by synthesizing the top-down method and nanowires using VLS (Vapor-Liquid Solide) growth method There is a way.

The conventional top-down method is to directly fabricate nanowires by etching silicon, and to form nanowires having diameters of several nanometers to several tens of nanometers, an ultra-fine pattern is required. Thus, E-beam lithography Ultrafine pattern forming process is used. This top-down method has the advantage of producing nanowires in a desired size at a desired location, but it is difficult to commercialize because the production speed is very slow because expensive equipment such as electron beam lithography must be used.

In addition, the characteristics of the nanowires fabricated by the top-down method are non-uniform compared to the nanowires fabricated by the self-aligning method, and in order to serve as an electrical device, the nanowires must be fabricated on an insulator, soy wafer. There is a downside to using it.

In addition, the conventional bottom-up VLS growth method is a nanowire of most semiconductors and metal materials such as silicon (Si), zinc oxide (ZnO), gallium nitride (GaN), indium phosphide (InP), and metal (metal). It is used for growth and is the most studied method in the field of nanowires.

However, in order to manufacture nanowire devices after growing the nanowires, the manufactured nanowires must be aligned in a desired position, and then additional structures such as electrodes must be manufactured.

Positioning of the nanowires through the alignment is a method such as electrophoresis, self-assembly method for aligning the nanowires to a desired position for nanowire device applications, or nanowires by fluid flow using rapeseed channels. Use the sorting method.

On the other hand, nanowire field effect transistors (FETs) for early diagnosis of liver cancer have recently been fused with BT and have been proven as a groundbreaking technology that can compensate for the shortcomings of surface analysis. It is in the process of establishing a concept as a biosensor. These nanowire biosensors have the advantage of measuring highly sensitive (<10-12g) antigens without indicators by functionalizing the surface to adsorb specific antibodies on the nanowire surface.

As a representative example of a biosensor based on low dimensional nanostructures, research on field effect transistor biosensors using carbon nanotubes (CNT) has been actively conducted worldwide.

Carbon nanotubes have been widely studied as biosensors, but they require separation technology due to mixed electrical properties such as metals and semiconductors, and silicon-based nanowires have a problem of natural oxide film formation when exposed to air.

Recently, ZnO nanowires are relatively inexpensive to produce compared to CNTs and Si and are expected to overcome the problems of existing one-dimensional nanomaterials. It is not developed.

An object of the present invention for solving such a conventional problem is to provide a method for producing nanowires capable of producing stable nanowires, such as insoluble in acid and basic solutions, blood, and the like.

The present invention for achieving the above object,

a) growing nanowires on the substrate;

b) forming a protective layer made of hydrocarbon or carbon fluoride on the surface of the nanowires by using a plasma; and providing a method for producing nanowires stable in an acid and basic atmosphere.

The substrate of step a) is a silicon substrate, sapphire, glass, a substrate coated with silicon on glass, indium tin oxide, mica, graphite, molybdenum sulfide, copper, zinc, aluminum, stainless, magnesium, iron, nickel , Gold, silver metal, polyimide, polyester, polycarbonate, acrylic resin.

The nanowire of step a) is made of any one selected from ZnO, SnO ₂ , Si, GaN.

In particular, the plasma deposition conditions in step b) is preferably 100 ~ 1000W power, 10 ~ 100mTorr pressure, 10 ~ 100sccm flow rate of the supply gas.

Hereinafter, the method for producing nanowires stable in the acid and basic atmosphere of the present invention will be described in detail.

Method of producing a nanowire stable in the acid and basic atmosphere of the present invention comprises the steps of growing a nanowire on a substrate, and forming a protective layer of hydrocarbon or carbon fluoride on the surface of the nanowire using a plasma Is done.

First, the nanowire growth step is a step of growing nanowires on a substrate, and methods of growing nanowires on a substrate include vapor phase-liquid phasesolid phase (VLS), solid-liquid-solid (SLS), and organic metals. Chemical vapor deposition (MOCVD: Metal Organic Chemical Vapor Deposition), MBE (Molecular Beam Epitaxy) method and the like.

The substrate usable in the present invention is not particularly limited, but may be a plastic substrate or a glass substrate, preferably a silicon substrate, sapphire, glass, a substrate coated with silicon on glass, indium tin oxide, mica, graphite And metal substrates such as molybdenum sulfide, copper, zinc, aluminum, stainless steel, magnesium, iron, nickel, gold, silver, polyimide, polyester, polycarbonate, and acrylic resin.

The type of the nanowires is not particularly limited, but may be formed of ZnO, SnO ₂ , Si, GaN, or the like. In particular, it is preferable that the nanowires are made of ZnO, which is low in manufacturing cost and obtains high quality single crystal nanowires.

The VLS method is described as an example of a method of growing ZnO nanowires as follows.

The VLS method is a method in which nanowire precursors transported in a high temperature furnace are grown on silicon nanowires by condensation and crystallization on the surface of a catalyst such as Au.

First, a catalyst layer made of Au or the like is deposited on a substrate. The substrate is placed in a reactor and heated while injecting a gas and a nanowire precursor to form a nanowire. The catalyst layer is made of Au, Ni, Ag, Pd, Pd / Ni, Ti, Co, Cr, Fe and the like, the gas is made of Ar, N2, He, H ₂ and the like.

Next, the protective layer deposition step is to deposit a protective layer on the surface of the nanowires in order to prevent the nanowires grown by the nanowire growth step to dissolve in acid and basic solutions, blood, etc. A protective layer is deposited on the surface of the nanowires with hydrocarbon or hydrogen fluoride.

The hydrocarbon is composed of CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₃ H ₈ and the like, hydrogen fluoride is composed of CF ₄ , C ₂ F ₆ , C ₄ F ₆ and the like.

When forming a protective layer of amorphous carbon using a hydrocarbon such as CH4, since the dielectric constant is low and the concentration of dangling bond is high, it is possible to prevent nanowires from dissolving in acid and basic solution as well as functional groups. ) Has a very advantageous advantage for the immobilization of proteinaceous antibodies because of the ease of adsorption.

And when forming a protective layer of Teflon like polymer using hydrogen fluoride, such as CF4 has the advantage that can prevent the nanowires are dissolved in strong acids, strong salts.

The plasma deposition conditions are preferably 100 to 1000 W, pressure 10 to 100 mTorr, and flow rate of 10 to 100 sccm of supply gas in order to uniformly deposit the protective layer of amorphous carbon or Teflon like polymer on the surface of the nanowire.

As described above, the nanowires prepared according to the present invention may be widely used for biosensors, biochips, and other various applications for early diagnosis of liver cancer.

As the protective layer of amorphous carbon or Teflon like polymer is formed on the surface of the nanowires prepared by the nanowire manufacturing method of the present invention, nanowires can be prevented from being dissolved in acid, basic solution, blood, etc. There is a widely available effect.

1 is a view schematically showing a manufacturing process of a nanowire,
2 is a SEM photograph of the synthesized ZnO nanowires,
3 is a view showing the results of diffraction analysis (X-ray diffraction, XRD) of the synthesized ZnO nanowires,
4 is a TEM photograph of the synthesized ZnO nanowires,
5 is an HRTEM photograph,
6 to 9 are electron micrographs of Example 1 exposed to 0 min, 10 min, 30 min, 60 min in an aqueous solution of pH 4,
10 and 11 are transmission electron micrographs of Example 1 exposed to an aqueous solution of pH 4 60 min,
12 and 13 are electron micrographs of the comparative example exposed to 0 min, 10 min in an aqueous solution of pH 4,
14 is a transmission electron microscope photograph of a comparative example exposed to an aqueous solution of pH 4 10 min,
15 is an XPS analysis result.

Hereinafter, the present invention will be described in detail with reference to Examples. The scope of the present invention is not limited to the following Examples.

Example 1

ZnO nanowires were prepared on the silicon substrate by using the VLS method as shown in FIG. 1. Au layer was deposited on the silicon substrate by thermal evaporation method, Zn powder was used for ZnO nanowire synthesis, and after slowly increasing the temperature to 900 ° C. for the first 30 minutes, N ₂ 20sccm, O ₂ The ZnO nanowires were grown by maintaining the pressure at 10 Torr for 30 minutes while supplying 5 sccm.

The shape of the synthesized ZnO nanowires was observed using a scanning electron microscope (SEM), and the X-ray diffraction (XRD) and transmission electron microscope (TEM) of the nanowires were used. The crystallographic properties were observed.

2 is a SEM photograph of the synthesized ZnO nanowires, the diameter of the synthesized nanowires is less than ~ 100nm, the length was several tens of ㎛. 3 shows XRD patterns of the synthesized ZnO nanowires, and all peaks show hexagonal wurtzite rutile structures. FIG. 4 shows TEM images and partial rotation patterns of the synthesized ZnO nanowires. The structure is shown.

A protective layer of amorphous carbon was formed on the surface of the ZnO nanowires thus prepared using plasma. Plasma deposition conditions were power 500W, pressure 100 Torr, C ₃ H ₈ was used as the feed gas, the flow rate was 10sccm.

The shape of the protective layer formed ZnO nanowires was observed by high-resolution transmission electron microscopy (HRTEM), the HRTEM photograph is shown in Figure 5, the protective layer of amorphous carbon is 7 nm thick ZnO nano It was formed uniformly on the surface of the wire.

[Stability Test in pH4 Aqueous Solution]

The ZnO nanowires in which the protective layer of amorphous carbon of Example 1 was formed were exposed to an aqueous solution of pH 4 for 10 minutes, and as a comparative example, ZnO nanowires in which the protective layer of amorphous carbon was not formed were used.

The degree of dissolution was observed using the scanning electron microscope (SEM) and the transmission electron microscope (TEM) at intervals of 10 minutes after exposure to an aqueous solution of pH 4 for Example 1 and Comparative Example.

6 to 9 are electron micrographs of Example 1 exposed to 0 min, 10 min, 30 min, and 60 min in an aqueous solution of pH 4, and FIGS. 10 and 11 are transmission electrons of Example 1 exposed to 60 min in an aqueous solution of pH 4. Photomicrograph. 12 and 13 are electron micrographs of a comparative example exposed to 0 min, 10 min in an aqueous solution of pH4, Figure 14 is a transmission electron micrograph of a comparative example exposed to 10 min in an aqueous solution of pH4.

In the case of Example 1 as shown in Figure 6 to 11 even when exposed to the pH 4 aqueous solution for more than 1 hour ZnO nanowires did not dissolve because the protective layer of amorphous carbon to protect the ZnO nanowires. However, as shown in FIGS. 12 to 14, in the comparative example, ZnO nanowires were dissolved in the SEM photograph exposed to the aqueous solution of pH 4 for 10 minutes.

[Stability Test in Aqueous Solutions of pH4, pH7 and pH10]

After functionalizing APTES (Aminopropyltriethoxysilane) required for immobilization of the AFP antibody on the ZnO nanowire having the protective layer of amorphous carbon of Example 1, the solution was exposed to an aqueous solution of pH 4, pH 7 and pH 10 for 60 minutes. And the surface was analyzed using x-ray photoelectron spectroscopy (XPS), the results are shown in FIG.

As a result of XPS analysis, as shown in FIG. 15, it was confirmed that there was no significant change in the molecular structure of the surface of the ZnO nanowires in which the protective layers of the amorphous carbon of Example 1 exposed to aqueous solutions of pH 4, pH 7 and pH 10 were formed.

Claims (9)

a) growing nanowires on the substrate;
b) forming a protective layer with hydrocarbons or fluorocarbons on the surface of the nanowires using plasma;
The method of claim 1,
The substrate of step a) is a silicon substrate, sapphire, glass, a substrate coated with silicon on glass, indium tin oxide, mica, graphite, molybdenum sulfide, copper, zinc, aluminum, stainless, magnesium, iron, nickel , Gold, silver metal, polyimide, polyester, polycarbonate, a method for producing nanowires stable in an acid and basic atmosphere, characterized in that consisting of an acrylic resin.
The method of claim 1,
The nanowire of step a) is ZnO, SnO ₂ , Si, GaN method for producing a stable nanowire in an acidic and basic atmosphere, characterized in that consisting of any one of.
The method of claim 3,
The nanowire of step a) is a method for producing nanowires stable in an acid and basic atmosphere, characterized in that consisting of ZnO.
The method of claim 1,
The step b) is a step of forming a protective layer with a hydrocarbon using a plasma on the surface of the nanowire, characterized in that the production method of the stable nanowire in an acid and basic atmosphere.
The method of claim 1,
b) forming a protective layer made of carbon fluoride on the surface of the nanowires using plasma;
Plasma deposition conditions in step b) is 100 ~ 1000W, pressure 10 ~ 100mTorr, nanowire coating method, characterized in that the flow rate of the supply gas 10 ~ 100sccm.
The protective layer is provided on the surface of the nanowire, the protective layer is stable in the acid and basic atmosphere, characterized in that formed with a hydrocarbon or carbon fluoride using a plasma
. 9. The method of claim 8,
The nanowire is stable in the acid and basic atmosphere, characterized in that made of any one selected from ZnO, SnO ₂ , Si, GaN.

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