KR100604130B1 - Core-removed nano structure and preparation thereof - Google Patents

Abstract

The present invention relates to a nanostructure with a core removed and a method for manufacturing the same. A multi-wall (core-shell) manufactured by coating various heterogeneous materials such as metals, semiconductors, and dielectrics on zinc oxide nanowires according to the present invention. The hollow nanostructure manufactured by removing zinc oxide, which is a core material, from a zinc oxide nanowire having a structure using a corrosive gas, an inorganic acid, a plasma, etc., has a volume to cross-sectional area ratio of more than twice that of the nanowire. Multi-functional integrated nano-devices and nano-systems can be provided by providing various characteristics and structures through the control of length and removal of core material and injection of foreign matters into empty spaces. It can be used to advantage.

Description

Core structure-free nanostructures and method for manufacturing the same {CORE-REMOVED NANO STRUCTURE AND PREPARATION THEREOF}             

1 is a basic structural diagram of a nanostructure from which a core is removed according to the present invention.

(a) shows a nanotube structure from which the center is removed,

(b) shows the multi-walled nanotube structure with the core removed;

(c) shows a nanocap structure with the core removed;

(d) represents a nanonote structure with the core removed;

2 is a basic structural diagram of a nano-device and a nano-system using the nanostructure from which the center is removed according to the present invention.

(a) is a structural diagram of a nano system such as a storage system and a delivery system using a nanostructure having a core removed therefrom,

(b) is a structural diagram of a nano device such as a high electron mobility transistor (HEMT), spintronics, etc. using the nanostructure having the core removed therein;

(c) is a structural diagram of a nano device such as a gas sensor, a photo-detector device, a rectifier, a light emitting diode (LED), etc. using the nanostructure having its core removed;

3 is a transmission electron micrograph (TEM) of a multi-walled nanowire and a multi-walled nanostructure having a core removed therefrom according to the present invention.

(a) is a transmission electron micrograph of a multi-walled nanowire without the core removed,

(b) is a transmission electron micrograph of the multi-walled nanostructure from which the center is removed,

(c) is a transmission electron micrograph of the multi-walled nanotubes, nanotees, and nanocaps with cores removed;

Figure 4 shows the results of the X-ray diffraction analysis (XRD) graph of the nanostructures (gallium nitride (GaN) nanotubes) is removed from the center according to the present invention.

The present invention relates to a nanostructure with a core removed and a method for manufacturing the same. Specifically, the core material is a core material in a zinc-oxide-based nanowire having a core-shell structure coated with various heterogeneous materials on zinc oxide. The present invention relates to a nanostructure obtained by removing zinc oxide using a corrosive gas, an inorganic acid, a plasma, and the like, and a method of manufacturing the same.

Semiconductor nanomaterials and nanostructures (e.g. carbon nanotubes) with a size of 100 nm or less not only show various physical properties depending on the type of material, but also quantized energy levels are formed according to the size, resulting in unique electrical and optical properties. see. In particular, nanostructures such as hollow nanotubes, nanotees, nanocaps, etc. have a small multi-wall thickness of 3 to 20 nm, which is excellent in quantum confinement effects, and have a biochemical sensor (more than twice as large as volume / cross-sectional area compared to nanowire). bio-chemical sensor) and the like can be used very advantageously. In addition, since the nanostructures from which the core is removed can exist in various three-dimensional shapes such as nanotubes, nanotees, and nanocaps, they are expected to be used as storage and delivery systems injecting various device materials. . For example, a drug or a magnetic material may be injected into the nanostructure to be used as a drug delivery system and a medical diagnostic screening agent.

In addition, semiconductor nanomaterials and nanostructures include next-generation displays and light emitting devices (FEDs), field effect transistors (FETs), photo-detector devices, and nonvolatile magnetic memory devices using one-dimensional semiconductor nanomaterials. In addition, various nanodevices such as diodes, rectifiers, and logic devices using p-type and n-type nanostructures have begun to receive much attention.

However, the existing nanostructures have a problem in that various nanostructures that can satisfy a desired function are implemented as a single nanostructure, and it is difficult to control the thickness, diameter, and internal volume of the nanostructures, thereby overcoming them and satisfying a desired function. There is a need for the development of nanostructures.

Accordingly, an object of the present invention is to remove the core of the zinc oxide nanowire of the multi-wall structure to control the shape and length, the degree of removal of the central oxide and the kind of foreign substances injected into the removed central portion, and various characteristics. And to provide a nanostructure and a method for manufacturing the nanostructure having a structure is removed.

In order to achieve the above object, in the present invention, a zinc oxide nanowire having a multi-wall structure is obtained by coating a heterometal such as a transition metal material, a nitride semiconductor, and a dielectric material on a zinc oxide nanowire prepared by an organometallic chemical vapor deposition method. Thereafter, there is provided a method of making a nanostructure, which is partially or wholly hollow in its center, including removing its core with a corrosive gas, inorganic acid, plasma, and the like.

In addition, the present invention provides nanostructures, which are partially or entirely hollow, having a diameter in the range of 5 to 30 nm, prepared by the method.

Hereinafter, the present invention will be described in more detail.

Specifically, the nanostructure of the form in which the center is partially or wholly removed according to the present invention, the zinc oxide of the multi-wall structure coated with various heterogeneous materials according to the intended use on the zinc oxide nanowires produced by the organometallic chemical vapor deposition method By removing zinc oxide, which is the central material in the linked nanowires, it is characterized in that the center is obtained in the form of the center is removed, such as nanotubes, nanocaps, nanoti.

The zinc oxide nanowires of the multi-wall structure used in the present invention have a purpose of controlling bandgap, electrical conductivity, adding magnetic materials, forming new nanowires or nanotubes on zinc oxide nanowires prepared by organometallic chemical vapor deposition. Various heterogeneous materials, such as transition metal materials, nitride semiconductors or dielectrics, may be prepared by chemical vapor deposition including spherical organometallic chemical vapor deposition, sputtering, thermal or electron beam evaporation, and pulsed laser. It can be obtained by coating by a vapor-phase transport process using a metal catalyst such as gold, preferably an organometallic chemical vapor deposition method, as well as physical growth methods such as pulse laser deposition.

For example, the material coated on the zinc oxide nanowires to control the band gap may include magnesium (Mg), cadmium (Cd), and the like, and these metals may be coated on the zinc oxide nanowires to form zinc oxide (ZnO). Zinc oxide (Zn _1-x Mg _x O, 0 <x <1) or zinc cadmium oxide (Zn _1-x Cd _x O, 0 <x <1) in the form of magnesium or cadmium Can be.

Manganese (Mn), cobalt (Co) and the like are used to make the magnetism, and according to the present invention by coating these transition metals on the zinc oxide nanowires zinc oxide doped with manganese or cobalt oxide Zinc manganese (Zn _1-x Mn _x O, 0 <x <1) or zinc cobalt (Zn _1-x Co _x O, 0 <x <1) and the like can be prepared.

In addition, a nitride semiconductor such as GaN, AlN, InN, or an alloy thereof may be coated on the zinc oxide nanowires to form new nanowires (nanotubes), and titanium oxide (TiO ₂ ) and nitride to control electrical conductivity. Zinc oxide nanowires having a multi-wall structure coated with a dielectric such as titanium (TiN), silicon oxide (SiO ₂ ), and barium titanium oxide (BaTiO ₃ ) may be prepared.

The zinc oxide nanowires used in the present invention are injected with zinc-containing organometallic and oxygen-containing gas or oxygen-containing organics into the reactor via separate lines, respectively, and have a pressure of 10 ^-5 to 760 mmHg and a temperature of 400 to It is prepared by an organometallic chemical vapor deposition method characterized by depositing and growing a zinc oxide-based nanowires on a substrate by chemical reaction of the precursors of the reactants under the reaction conditions of 900 ℃. Zinc-containing organometallics used in the present invention include dimethyl zinc [Zn (CH ₃ ) ₂ ], diethyl zinc [Zn (C ₂ H ₅ ) ₂ ], zinc acetate [Zn (OOCCH ₃ ) ₂ H ₂ O. ], Zinc acetate anhydride [Zn (OOCCH ₃ ) ₂ ], zinc acetylacetonate [Zn (C ₅ H ₇ O ₂ ) ₂ ], and the like.

In addition, the oxygen-containing gas used in the present invention may include O ₂ , O ₃ , NO ₂ , water vapor, CO ₂ and the like, the oxygen-containing organic substance may include C ₄ H ₈ O, The diameter, length and density of the zinc oxide nanowires prepared according to the present invention can be variously adjusted according to the growth temperature, pressure and flow rate of the reactant.

Zinc oxide nanowires having a multi-wall structure can be prepared by coating a heterogeneous material using various precursors known in the art, preferably using organometallic chemical vapor deposition on the prepared zinc oxide nanowires.

In other words, by injecting the reaction precursors of the material to be coated into the reactor through separate lines, and chemically reacting under a reaction condition of a pressure of 10 ^-5 to 760 mmHg and a temperature of 400 to 900 ℃, the heterogeneous material on the zinc oxide nanowires Can be coated. Since the thickness of the coating film increases in proportion to the growth time, the reaction time was maintained for a time that the film having a thickness of about several tens of nanometers was grown.

Magnesium-containing organometals, which are used in coating, include biscyclopentadienyl magnesium [bis-cyclopentadienyl magnesium, (C ₅ H ₅ ) ₂ Mg], bismethylcyclopentadienyl magnesium [bis-methylcyclopentadienyl-Mg]. , (CH ₃ C ₅ H ₄ ) ₂ Mg], bisethylcyclopentadienyl magnesium [bis-ethylcyclopentadienyl-Mg, (C ₂ H ₅ C ₅ H ₄ ) ₂ Mg], bispentamethylcyclopentadienyl magnesium [ bis-pentamethylcyclopentadienyl-Mg, {(CH ₃ ) ₅ C ₅ } ₂ Mg], magnesium acetate [Mg (OOCCH ₃ ) ₂ .2H ₂ O], magnesium acetate anhydride [Mg (OOCCH ₃ ) ₂ ], magnesium acetylacetonate [Mg (C ₅ H ₇ O ₂ ) ₂ .H ₂ O], and the like. Examples of the cadmium-containing organic metal include diethyl cadmium. Examples of the manganese-containing organic metal include biscyclopenta. Dienyl manganese etc. are mentioned, for example. Examples of the gallium-containing organic metal include trimethyl gallium (TMGa) and triethyl gallium (TEGa). Examples of the aluminum-containing organic metal include trimethyl aluminum (TMAl) and triethyl aluminum (TEAl). Examples of the indium-containing organic metal include trimethylindium (TMIn), and the titanium-containing organic metal includes tetrakis diethylamido titanium, Ti {N (C ₂ H _5). ) ₂ } ₄ ], Tetrakis dimethylamido titanium, Ti {N (CH ₃ ) ₂ } ₄ ], titanium tert-butoxide, Ti {O (tC ₄ H ₉ )} ₄ ], titanium ethoxide, Ti (OC ₂ H ₅ ) ₄ , titanium isopropoxide, Ti {O (iC ₃ H ₇ ) ₄ }], and the like.

By removing the zinc oxide which is the central material of the zinc oxide-based nanowires of the multi-wall structure prepared along the length of the nanowires, a nanostructure in which the center portion is removed may be manufactured.

The basic structure of the nanostructure from which the center is removed according to the present invention is a single-walled or multi-walled nanotube structure in which the center is entirely removed as shown in FIGS. 1 (a) and 1 (b), respectively; As shown in Figure 1 (c) nanocap (nanocap) structure is partially removed; Or one or more multi-walled nanostructures having a hollow center, such as a nanonote structure shown in FIG.

In the method of the present invention, as a method of removing the central portion of the multi-walled zinc oxide nanowires, conventional methods such as dry, wet or etching techniques used in semiconductor processing techniques may be used. The present invention can be applied not only to a zinc oxide nanowire having a multi-wall structure in which the central portion is an oxide, but also to a nanowire having a multi-wall structure in which the central portion is not an oxide.

Specifically, the method of removing the central portion of the zinc oxide-based nanowire of the multi-wall structure using a corrosive gas, an inorganic acid or a plasma is as follows.

1) Fabrication of decentered nanostructures using corrosive gases

Examples of the corrosive gas used in the present invention include ammonia (NH ₃ ), boron trichloride (BCl ₃ ), and the like. The corrosive gas is injected into the reactor, and the pressure and temperature of 10 ^-5 to 760 mmHg are 100 to 900 ° C. By chemical reaction with the zinc oxide nanowire of the multi-wall structure under the reaction conditions for 10 minutes to 1 hour, it is possible to manufacture a nanostructure from which the center is removed. The extent to which zinc oxide, which is the central part of the zinc oxide nanowire of the multi-wall structure, is removed can be controlled according to reaction conditions such as reaction temperature, pressure and time. Therefore, the zinc oxide, which is a central part, may be entirely removed along the length of the nanowires to prepare nanotubes, or partially removed to prepare nanostructures such as nanocaps.

2) Fabrication of Nanostructures with Center Removed Using Inorganic Acids

As the inorganic acid used in the present invention, an acid used in a conventional semiconductor process, preferably hydrochloric acid, nitric acid, or the like can be used, and an acid aqueous solution having a concentration of 1 to 40% (by volume), preferably 1 to 10% The zinc oxide nanowires having the multi-wall structure are immersed in the mixture for 1 minute to 1 hour and chemically reacted with the zinc oxide-based nanowires having the multi-wall structure. The extent to which zinc oxide, the central material of zinc oxide nanowires of multi-wall structure, is removed is proportional to the concentration of acid and reaction time.If the concentration of acid is higher than 40%, the nanostructure may be damaged. Zinc oxide removal is minimal.

3) Fabrication of the decentered nanostructure using plasma

Using a plasma such as nitrogen or hydrogen gas, the center portion of the zinc oxide nanowire of the multi-wall structure is etched for 30 minutes to 2 hours at a temperature ranging from 100 to 800 ° C. to remove the center structure along the length of the nanowire. It can manufacture. The degree to which zinc oxide, which is the central material of the zinc oxide nanowire of the multi-wall structure, is removed depends on the power and gas amount when the nitrogen or hydrogen gas is plasma, the reaction temperature and time. Etch rates are so fast that multi-walled nanostructures can be damaged.

According to the method according to the invention it is possible to produce nanostructures in the form of partially or wholly removed cores ranging in diameter from about 5 to 30 nm, the shape and multi-wall thickness of the nanostructures to be produced are determined by temperature, pressure, reaction By varying the reaction conditions such as time, reactants, and the flow rate of the reactants, it can be variously controlled by controlling the degree of oxide removal in the center portion of the nanowire of the multi-wall structure.

The multi-walled nanostructures formed in accordance with the present invention may be partially or completely empty, and used as a storage and delivery system by injecting a material of a desired use into an empty center portion as shown in FIG. As shown in FIG. 2 (b), a high electron mobility transistor (HEMT), a spin device, and the like using a hollow multi-walled nanostructure doped in an outer wall region and not dope inside As shown in FIG. 2 (c), it is used for nano devices such as gas sensors, photodetecting devices, rectifiers, light emitting diodes, and the like which are not only excellent in stability and device efficiency but also easy to integrate through pn junctions. May be

As described above, the hollow nanostructures prepared according to the present invention have a volume-to-cross-sectional ratio greater than twice as large as that of the multi-walled nanowires, and can inject various foreign matters into the empty center portion, and the shape and length of the nanostructures, It may be manufactured to have a variety of characteristics and structures through the control of the thickness of the multi-wall, it can be advantageously used in the multi-function integrated nano device because the core parts of various nano devices can be manufactured in a single nano structure.

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited only to the following examples.

Preparation Example 1 Preparation of Zinc Oxide Nanowire (GaN / ZnO) of Multi-Wall Structure

Argon was used as a carrier gas via separate lines to inject the reaction precursors, dimethyl zinc (Zn (CH ₃ ) ₂ ) and O ₂ gases into the reactor at flow rates ranging from 0.1 to 10 sccm and 10 to 100 sccm, respectively. By chemically reacting the materials on the substrate, zinc oxide nanowires were deposited and grown. The pressure in the reactor was maintained at 10 ⁻⁵ to 760 mmHg and the temperature at 400 to 900 ° C. during the growth of the nanowires over about 1 hour.

Subsequently, trimethyl gallium (TMGa) and NH ₃ gases were introduced into the reactor through a separate line at flow rates ranging from 1 to 50 sccm and 100 to 2000 sccm, respectively, while maintaining the pressure at 760 torr and the temperature at 500 ° C. The reaction precursors were chemically reacted in the reactor for 1 to 10 minutes to prepare gallium nitride (GaN) / zinc oxide (ZnO) nanowires having a multi-wall structure coated with gallium nitride (GaN) on the zinc oxide nanowires.

Preparation Example 2 Preparation of Zinc Oxide Nanowire (AlN / ZnO) of Multi-Wall Structure

Zinc oxide oxide was prepared in the same manner as in Example 1 except that TMAl (trimethyl aluminum) was used instead of TMGa as the reaction precursor of the material to be coated on the zinc oxide nanowires, and the pressure in the reactor was 5 torr. An aluminum nitride (AlN) / zinc oxide (ZnO) nanowire having a multi-wall structure coated with aluminum nitride (AlN) was prepared on the route.

Preparation Example 3 Preparation of Zinc Oxide Nanowire (AlN / GaN / ZnO) of Multi-Wall Structure

The multi-walled gallium nitride / zinc oxide nanowires prepared in Example 1 were placed in the reactor, respectively, and the individual lines gave TMAl and NH ₃ gas in the reactor at flow rates ranging from 1 to 50 sccm and 100 to 2000 sccm, respectively. In the reactor, while maintaining the pressure at 5 torr and maintaining the temperature at 500 ° C., the reaction precursors were chemically reacted in the reactor for 1 to 10 minutes to form aluminum nitride (AlN) on the gallium nitride / zinc oxide nanowire having a multi-wall structure. The coated multi-walled aluminum nitride (AlN) / gallium nitride (GaN) / zinc oxide (ZnO) nanowires were prepared.

Preparation Example 4 Preparation of Zinc Oxide Nanowire (GaN / AlN / ZnO) of Multi-Wall Structure

The multi-walled aluminum nitride / zinc oxide nanowires prepared in Example 2 were placed in a reactor and TMGa and NH ₃ gases were introduced into the reactor at separate flow rates in the range of 1 to 50 sccm and 100 to 2000 sccm, respectively. The reaction precursors were chemically reacted in the reactor for 1 to 10 minutes while maintaining the pressure at 760 torr and the temperature at 500 ° C., so that gallium nitride (GaN) was deposited on the multi-walled aluminum nitride / zinc oxide nanowires. Coated multi-walled gallium nitride (GaN) / aluminum nitride (AlN) / zinc oxide (ZnO) nanowires were prepared.

Examples 1-4: Fabrication of Decentralized Nanostructures Using Corrosive Gas

Zinc oxide nanowires having a multi-wall structure prepared in Preparation Examples 1 to 4 were placed in a reactor, NH ₃ gas was injected into the reactor at a flow rate in the range of 100 to 2000 sccm, and the pressure in the reactor was 10 to ⁵ to. Hollow nanostructures were prepared by removing the central portion of the multi-walled zinc oxide nanowires for about 15 minutes while maintaining the temperature at 400-900 ° C. at 760 mmHg.

Examples 5 to 9: Preparation of Centered Nanostructures Using Inorganic Acids

The zinc oxide nanowires of the multi-wall structure prepared in Preparation Examples 1 to 4 were immersed in a hydrochloric acid or nitric acid solution at a concentration of 1 to 10% at room temperature for about 1 minute to 1 hour to remove zinc oxide, which is the main material. Observation produced a hollow nanostructure.

Examples 9-12: Fabrication of Decentralized Nanostructures Using Plasma

The zinc oxide nanowires of the multi-wall structure prepared in Preparation Examples 1 to 4 were placed in a reactor, and then hydrogen or nitrogen gas was injected into the reactor at a flow rate of 50 to 300 sccm to supply plasma at a power of 50 to 300 W. The hollow nanostructure was prepared by removing the zinc oxide for 30 minutes to 2 hours while maintaining the temperature of the reactor in the range of 500 to 800 ° C.

A transmission electron micrograph (TEM) of a zinc oxide nanowire having a multi-wall structure prepared in Example 1 is shown in FIG. 3 (a), and a transmission electron micrograph of the nanostructure manufactured by removing a central portion thereof is shown. 3 (b), the transmission electron micrographs of the nanotubes, nanocaps and nano-tee structure of the prepared nanostructures are shown in Figure 3 (c). From FIG. 3, it can be seen that multi-walled nanostructures with a core removed, having a large diameter of 5-100 nm and a length of about 0.5 to 5 μm, have been successfully manufactured.

Figure 4 shows the results of the X-ray diffraction analysis (XRD) graph of the gallium nitride nanotubes prepared by removing the center of the multi-wall gallium nitride / zinc oxide nanowires prepared in Example 1, zinc oxide nanowires Silver 34.4 ° gallium nitride nanotubes were obtained with diffraction angle at 34.6 °, indicating that nanostructures without zinc oxide, the central material of multi-walled gallium nitride / zinc oxide nanowires, were successfully fabricated.

According to the present invention, a hollow nanostructure manufactured by removing a central portion of a multi-walled zinc oxide nanowire using a corrosive gas, an inorganic acid, a plasma, or the like has a biochemical sensor having a volume-to-cross-sectional area ratio of more than twice that of the nanowire. It can be used very advantageously and the like, and can have various characteristics and structures through the adjustment of the shape and length and the degree of zinc oxide removal, and the injection of foreign matter into the empty space. In addition, the core components of various nanodevices, which can be applied to storage and delivery systems, biotechnology and fine chemistry, can be fabricated into a single nanostructure to realize multi-functional integrated nanodevices and nanosystems.

Claims (11)

delete delete delete delete delete Zinc oxide nanowires having a core-shell structure were obtained by vapor-coating a transition metal material, a nitride semiconductor, or a dielectric on the zinc oxide nanowires prepared by organometallic chemical vapor deposition. Method for producing a nanostructure in the form of nanotubes, nano-tees or nanocaps having a diameter in the range of 5 to 30 nm, including removing a wholly or partially along the length of the nanowires. The method of claim 6, Removing the center of zinc oxide using a corrosive gas, inorganic acid or plasma. The method of claim 6, The corrosive gas is ammonia (NH ₃ ) or boron trichloride (BCl ₃ ). The method of claim 6, The inorganic acid is a solution of hydrochloric or nitric acid at a concentration of 1 to 40%. The method of claim 6, Wherein the plasma is generated from hydrogen or nitrogen gas. delete

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