JP2006096591A - Metal oxide structure and its production method, and metal oxide particle and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal oxide structure having either acicular or rod-like shape and a method for producing the same efficiently at a low cost, and a metal oxide particle and its production method. <P>SOLUTION: The metal oxide structure is obtained by dipping a substrate, having a crystal face comprising a metal-containing material with a regular crystal orientation structure to a fixed orientation, in a reaction solution, in which the metal oxide can be deposited, and depositing the metal oxide crystal on the crystal face comprising the metal-containing material. A preferable embodiment is that the crystal face comprising the metal-containing material is formed from either a single crystal material or an epitaxial crystal material. Another preferable embodiment is that the crystal face comprising the metal-containing material contains a metal, a metal oxide or a metal nitride. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to electronic materials and optical materials such as ceramic capacitors, actuators, light wavelength conversion elements, laser oscillation elements, cold cathode elements, surface modifiers for antibacterial and antifouling effects, gas phase and liquid phase The present invention relates to a metal oxide structure effective for a catalyst in at least one of the phases or a support thereof, a manufacturing method thereof, and metal oxide particles and a manufacturing method thereof.

Conventionally, as an apparatus for forming a metal oxide film on a substrate, for example, a metal compound capable of reacting after being released into the atmosphere to form a metal oxide is heated and used as a volatile gas body. An open air CVD (Chemical Vapor Deposition) apparatus that sprays and deposits a metal oxide on a substrate surface has been proposed (see Patent Document 1). A whisker-like or needle-like metal oxide structure obtained by using the CVD apparatus described in Patent Document 1 has been proposed (see Patent Document 2). In Non-Patent Document 1, it is reported that zinc oxide (ZnO) is electrochemically heteroepitaxially grown on gallium nitride (GaN).
It is known that a structure in which a whisker-like or needle-like metal oxide is formed on a substrate under atmospheric pressure can be produced.

  However, these prior art methods require large-scale equipment, are expensive, and are difficult to control conditions, and have either a needle-like shape or a bar-like shape with a uniform size over a large area. It is difficult to produce a metal oxide structure efficiently and at low cost, and further improvement and development are desired at present.

JP 2000-38671 A JP 2000-159599 A Appl. Phys. Lett. Vol. 75, no. 24, 13 December 1999 p. 3817-3819

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides a metal oxide structure capable of efficiently producing a metal oxide structure having either a needle shape or a rod shape, a method for producing the metal oxide structure, and a metal oxide particle and a method for producing the metal oxide structure. The purpose is to provide.

Means for solving the problems are as follows. That is,
<1> A substrate having a crystal plane containing a metal-containing material having a regular crystal orientation structure in a fixed orientation is immersed in a reaction solution capable of depositing a metal oxide to form a metal on the crystal plane containing the metal-containing material. A method for producing a metal oxide structure, characterized by depositing oxide crystals.
<2> The method for producing a metal oxide structure according to <1>, wherein the substrate is disposed so that a crystal plane including the metal-containing material faces downward and is immersed in a reaction solution.
<3> The method for producing a metal oxide structure according to any one of <1> to <2>, wherein the crystal plane including the metal-containing material is formed from at least one of a single crystal material and an epitaxial crystal material. is there.
<4> The method for producing a metal oxide structure according to any one of <1> to <3>, wherein the crystal plane containing the metal-containing material is the same crystal plane as the plane orientation of the substrate having the crystal plane. is there.
<5> The production of a metal oxide structure according to any one of <1> to <4>, wherein the crystal plane containing the metal-containing material is a crystal plane perpendicular to the c-axis direction of the substrate having the crystal plane. Is the method.
<6> When the lattice constant in the a-axis direction of a substrate having a crystal plane containing a metal-containing material is A, and the lattice constant in the a-axis direction of a metal oxide crystal deposited on the crystal plane is A ₀ , The method for producing a metal oxide structure according to any one of <1> to <5>, wherein the misfit rate represented by 1 is 48% or less.
<Formula 1>
Misfit rate (%) = [(A−A ₀ ) / A ₀ ] × 100
<7> The method for producing a metal oxide structure according to any one of <1> to <6>, wherein the crystal plane containing the metal-containing material contains a metal oxide.
<8> The method for producing a metal oxide structure according to any one of <1> to <7>, wherein the crystal plane containing the metal-containing material contains zinc oxide (ZnO).
<9> The method for producing a metal oxide structure according to any one of <1> to <7>, wherein the crystal plane containing the metal-containing material contains sapphire (Al ₂ O ₃ ).
<10> The method for producing a metal oxide structure according to any one of <1> to <6>, wherein the crystal plane containing the metal-containing material contains a metal nitride.
<11> The method for producing a metal oxide structure according to <10>, wherein the metal nitride is gallium nitride (GaN).
<12> The method for producing a metal oxide structure according to <11>, wherein the gallium nitride (GaN) is gallium nitride formed by a metal organic chemical vapor deposition method (MOCVD method).
<13> The method for producing a metal oxide structure according to any one of <1> to <12>, wherein the metal oxide deposited on the crystal plane containing the metal-containing material has a wurtzite crystal.
<14> The method for producing a metal oxide structure according to any one of <1> to <13>, wherein the metal oxide deposited on the crystal plane containing the metal-containing material is zinc oxide (ZnO).
<15> The metal oxidation according to any one of <1> to <14>, wherein the reaction solution contains at least one selected from Zn and a salt thereof, a hydroxide of Zn, and a hydrate of Zn. It is a manufacturing method of a structure.
<16> The method for producing a metal oxide structure according to any one of <1> to <15>, wherein the reaction solution contains a complexing agent.
<17> A metal oxide crystal having an aspect ratio of 1 or more produced by the method for producing a metal oxide structure according to any one of <1> to <16> is provided on a substrate. It is a metal oxide structure.
<18> The metal oxide particle according to <17>, wherein the metal oxide crystal has any one of a needle shape and a rod shape.
<19> A method for producing metal oxide particles, comprising producing metal oxide particles by separating the metal oxide structure according to any one of <17> to <18> from a substrate.
<20> The method for producing metal oxide particles according to <19>, wherein the separation is performed by cutting a metal oxide crystal deposited on a substrate from a root of the metal oxide crystal.
<21> Separation is the method for producing metal oxide particles according to <19>, wherein only the substrate is dissolved and removed from the substrate on which the metal oxide crystal is deposited.
<22> Metal oxide particles having an aspect ratio of greater than 1 produced by the method for producing metal oxide particles according to any one of <19> to <21>.
<23> The metal oxide particle according to <22>, wherein the metal oxide particle has any one of a needle shape and a rod shape.

  According to the present invention, conventional problems can be solved, and a metal oxide structure and metal oxide particles having either a needle shape or a rod shape can be produced efficiently and at low cost. The metal oxide structure and metal oxide particles of the present invention include insulators, conductors, solid electrolytes, fluorescent display tubes, EL elements, ceramic capacitors, actuators, laser oscillation elements, cold cathode elements, ferroelectric memories, piezoelectrics. Body, thermistor, varistor, superconductor, electronic material such as printed circuit board, electromagnetic shielding material, photodielectric, optical switch, optical sensor, solar cell, optical wavelength conversion element, optical element such as light absorption filter, temperature sensor , Sensor materials such as gas sensors, surface modifiers, surface protective agents, antireflective agents, surface modifiers for antibacterial and antifouling effects, catalysts in the gas phase, liquid phase, and both phases, and their carriers It is widely used for etc.

(Metal oxide structure, method for producing metal oxide structure, metal oxide particles, and method for producing metal oxide particles)
In the method for producing a metal oxide structure of the present invention, a substrate having a crystal plane containing a metal-containing material having a regular crystal orientation structure at least in a certain orientation is immersed in a reaction solution capable of depositing a metal oxide. And a step of depositing a metal oxide crystal on the crystal plane containing the metal-containing material, and further including other steps as necessary.
The metal oxide structure of the present invention has, on a substrate, a metal oxide having an aspect ratio of 1 or more produced by the method for producing a metal oxide structure of the present invention.
The method for producing metal oxide particles of the present invention comprises a step of producing metal oxide particles by separating the metal oxide structure of the present invention from a substrate.
The metal oxide particles of the present invention can be obtained by the method for producing metal oxide particles of the present invention.
Hereinafter, through the description of the method for producing the metal oxide structure of the present invention, the details of the metal oxide structure of the present invention, the method of producing the metal oxide particles of the present invention, and the details of the metal oxide particles of the present invention are also clarified. To.

-Board-
The substrate on which the metal oxide crystal is deposited is not particularly limited as long as it has a crystal plane containing a metal-containing material having a regular crystal orientation structure in a certain direction, and is appropriately selected according to the purpose. For example, a substrate formed of at least one of a single crystal material and an epitaxial crystal material is preferable.
In this case, the entire substrate may be formed from at least one of a single crystal material and an epitaxial crystal material, but at least a crystal plane on which a metal oxide is deposited is formed from at least one of the single crystal material and the epitaxial crystal material. If it is, there is no particular limitation.

The single crystal material means a single crystal, that is, a crystal growing along a certain crystal axis throughout the substrate. Even if the outer shape does not consist of a specific crystal plane, it is a single crystal as long as the crystal orientation maintains a constant orientation.
The epitaxial crystal material means a material in which a crystal thin film having the same plane orientation as the substrate is grown on a single crystal substrate. When the substrate and the thin film material are the same element, it is called a homoepitaxial material. On the other hand, a case where a thin film material and a substrate element are different is called a heteroepitaxial material.
Note that whether the crystal plane containing the metal oxide is a single crystal material or an epitaxial crystal material depends on the diffraction peak obtained by X-ray diffraction (XRD) measurement, lattice image observation with a high-resolution transmission electron microscope, It can be confirmed by a line diffraction image or the like.

The crystal plane containing the metal-containing material is preferably the same crystal plane as the plane orientation of the substrate having the crystal plane from the viewpoint of forming a highly crystalline material. In addition, it is preferable that the crystal plane containing the metal-containing material is a crystal plane perpendicular to the c-axis direction of the substrate having the crystal plane in terms of forming a highly crystalline material.
Here, when the lattice constant in the a-axis direction of the substrate having a crystal plane containing the metal-containing material is A, and the lattice constant in the a-axis direction of the metal oxide crystal deposited on the crystal plane is A ₀ , The misfit rate represented by Formula 1 is preferably 48% or less, and more preferably 5% or less. If the misfit rate exceeds 48%, consistency at the interface cannot be obtained, and the material may contain many defects.
<Formula 1>
Misfit rate (%) = [(A−A ₀ ) / A ₀ ] × 100

The metal-containing material in the crystal plane containing the metal-containing material is not particularly limited as long as it is a metal-containing material, and can be appropriately selected according to the purpose. Metal material; material containing metal ions; Examples thereof include metal compound materials such as metal oxides and metal nitrides.
The metal oxide is not particularly limited and may be appropriately selected depending on the purpose, for example, zinc oxide (ZnO), sapphire (high-purity alumina (Al 2 _{O 3)} single crystal), silicon oxide Titanium, MgO, In ₂ O ₃ , SiO ₂ , SnO ₂ , SnO ₂ , barium titanate, SrTiO ₃ , PZT, YBCO (YBaCu ₃ O _7-x ), YSZ (yttrium stabilized zirconia), YAG (Y ₃ Al ₅ O ₁₂ or 3Y ₂ O ₃ .5Al ₂ O ₃ ), ITO (In ₂ O ₃ / SnO ₂ ), and the like are preferable.

Moreover, it is preferable that the crystal plane containing the said metal containing material contains a metal nitride. There is no restriction | limiting in particular as this metal nitride, According to the objective, it can select suitably, For example, a gallium nitride (GaN) etc. are mentioned, For example, in the case of depositing a zinc oxide (ZnO), it is a ZnO crystal | crystallization. In particular, gallium nitride (GaN) is preferable in that it has a low misfit rate.
The gallium nitride (GaN) is preferably gallium nitride formed by metal organic chemical vapor deposition (MOCVD). Here, the metal organic chemical vapor deposition method (MOCVD method) is a CVD method using an organic metal as a raw material, and is a method of depositing a film by a chemical reaction by supplying a gas as a raw material to the substrate surface. For example, gallium nitride can be epitaxially grown by MOCVD on the c-plane of a sapphire single crystal.

-Metal oxide-
The metal oxide to be deposited (grown) on the substrate is not particularly limited and may be appropriately selected depending on the intended purpose. However, a metal oxide having a wurtzite crystal is a high crystal with few defects. It is preferable in that a conductive material can be formed.
The metal oxide to be deposited on the substrate is not particularly limited and may be appropriately selected depending on the purpose, for _{example, ZnO, MgO, Al 2 O} 3, In 2 O 3, SiO 2, SnO 2, SnO ₂ , TiO ₂ , barium titanate, SrTiO ₃ , PZT, YBCO (YBaCu ₃ O _7-x ), YSZ (yttrium stabilized zirconia), YAG (Y ₃ Al ₅ O ₁₂ or 3Y ₂ O ₃ .5Al ₂ O ₃ ), ITO (In ₂ O ₃ / SnO ₂ ), and the like.

  The method for depositing (growing) metal oxide crystals on the substrate is not particularly limited and may be appropriately selected depending on the purpose. For example, the substrate is placed in a reaction solution capable of depositing metal oxide crystals. A crystal growth method in an aqueous solution in which metal oxide crystals are deposited on a crystal plane containing the metal oxide by immersion is preferable because it does not require expensive equipment and is a low-cost and low-temperature process.

The reaction solution capable of precipitating the metal oxide is not particularly limited as long as the metal oxide crystal can be precipitated, and can be appropriately selected according to the purpose. The metal oxide source, complexing agent, solvent, pH It contains a regulator and the like.
The metal oxide source can be appropriately selected according to the type of metal oxide to be deposited on the substrate. For example, when zinc oxide (ZnO) is grown on the substrate, Zn and its salt, and Zn Of these, at least one selected from hydroxides and hydrates of Zn is preferred.
Examples of the Zn salt include Zn sulfide (for example, ZnSO ₄ .7H ₂ O) Zn nitrate (for example, Zn (NO ₃ ) ₂ ), Zn chloride (for example, ZnCl _2, etc.) ) And the like.
There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, For example, water, methanol, ethanol, isopropyl alcohol, etc. are mentioned.
There is no restriction | limiting in particular as said complexing agent, According to the objective, it can select suitably, For example, ammonium chloride, ammonium nitrate, ammonium sulfate, etc. are mentioned.
The pH of the reaction solution is preferably 8.0 to 11.0, and more preferably 9.0 to 10.0. The pH of the reaction solution preferably has a small fluctuation until completion of the growth of the metal oxide crystal and the substrate is taken out of the reaction solution, and the pH fluctuation is preferably 1 or less. The pH of the reaction solution is adjusted using a pH adjuster. Examples of the pH adjuster include NaOH, KOH, NH ₄ OH and the like.
The temperature of the reaction solution is preferably 40 to 90 ° C, more preferably 50 to 70 ° C.

  In the method for producing a metal oxide structure of the present invention, as shown in FIG. 2, the substrate 1 is placed in a reaction vessel 10 so that the crystal plane containing the metal-containing material faces downward, and the reaction solution 3 It is preferable to immerse in and form the metal oxide film 2 on the crystal plane. When the substrate is placed upward in the reaction solution and reacted, precipitation may occur on the surface of the substrate, which may inhibit the precipitation of metal oxide crystals.

Here, an example of the method for producing the metal oxide structure of the present invention will be specifically described by taking as an example the case of growing zinc oxide on a sapphire substrate.
As shown in FIG. 1, first, in a beaker 10 as a reaction vessel, ZnSO ₄ .7H ₂ O as a metal oxide source was stirred in water for 1 hour so that [Zn ²⁺ ] was 0.02M. Dissolved. NH ₄ Cl as a complexing agent is stirred in this solution for 30 minutes so that Ra = [NH ⁴⁺ ] / [Zn ²⁺ ] = 30 to prepare a mother liquor with [Zn ²⁺ ] of 0.02M. .
Next, water and an aqueous NaOH solution were added to the obtained mother liquor so that [Zn ²⁺ ] was 0.01 M and pH = 9.5 to prepare a ZnO crystal growth solution.
In the obtained solution for ZnO crystal growth, as shown in FIG. 2, it arrange | positioned so that the crystal plane which precipitates the ZnO crystal | crystallization of a board | substrate might become the lower side, and it immersed for 24 hours at 60 degreeC. The substrate was removed and dried. The pH of the reaction solution after removing the substrate was 9.41.

The metal oxide structure produced by the method for producing a metal oxide structure of the present invention preferably has an aspect ratio larger than 1, and preferably has one of a needle shape and a rod shape. The aspect ratio represents the ratio between the length and the diameter of the metal oxide structure, and the larger the value, the better.
In the metal oxide structure, metal oxide crystals in either a needle shape or a bar shape are vertically arranged on a substrate. For example, an insulator, a conductor, a solid electrolyte, a fluorescent display tube, an EL element , Ceramic capacitors, actuators, laser oscillation elements, cold cathode elements, ferroelectric memories, piezoelectric bodies, thermistors, varistors, superconductors, printed circuit boards and other electronic materials, electromagnetic shielding materials, photodielectrics, optical switches, light Sensors, solar cells, optical wavelength conversion elements, optical elements such as light absorption filters, sensor materials such as temperature sensors and gas sensors, surface modifiers, surface protective agents, antireflective agents, antibacterial, antifouling effects, etc. It can be used as a surface modifier, a catalyst in a gas phase, a liquid phase, or both phases, a carrier thereof, and the like.

  The method for producing metal oxide particles of the present invention comprises a step of producing metal oxide particles by separating the metal oxide structure of the present invention from the substrate, and further comprises other steps as necessary. Become.

As the separation, for example, (1) a mode in which the metal oxide crystal deposited on the substrate is cut from the base, and (2) a mode in which only the substrate is dissolved and removed from the substrate on which the metal oxide crystal is deposited are preferable.
Examples of the method (1) of cutting the metal oxide crystal deposited on the substrate from the base include laser irradiation, vibration, ultrasonic waves, and cutting with a nanocutter.
Examples of the method of dissolving and removing only the substrate of (2) include, for example, a method of removing using a chemical that dissolves only the substrate, a method in which a protective agent is applied to the metal oxide crystal deposited on the surface, and the substrate is used by using the chemical. And the like.

The metal oxide fine particles produced by the method for producing metal oxide fine particles of the present invention preferably have an aspect ratio larger than 1, and preferably have one of a needle shape and a rod shape. The aspect ratio represents the ratio between the length and the diameter of the metal oxide fine particles, and the larger the value, the more preferable.
The average particle length of the metal oxide fine particles is preferably 0.05 to 30 μm, and more preferably 0.05 to 5 μm. When the average particle length exceeds 30 μm, it may be greatly affected by scattering, and the adaptability to optical applications may be reduced.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Example 1
A sapphire (Al ₂ O ₃ ) substrate was used as the single crystal substrate. The c-plane (0001) of the sapphire substrate was used as a crystal plane containing a metal-containing material having a regular crystal orientation structure in a fixed orientation. Table 1 shows the lattice constant and misfit rate of the substrate. FIG. 3 shows a diffraction pattern of this sapphire substrate by an X-ray diffractometer (XRD) according to the following measurement conditions. From the result of FIG. 3, it is recognized that the c-plane (0001) of the sapphire substrate is formed of a single crystal material.

<XRD measurement conditions>
・ Rigaku, RAD = C
・ CuKα
・ Scanning Mode: 2θ / θ
・ Scanning Type: continuous
・ X-Ray: 50kV / 120mA
Divergent slit: 1 deg.
Scattering slit: 1 deg.
・ Reception slit: 0.15mm
・ Start: 20
・ Stop: 70
-Step: 0.01

First, as shown in FIG. 1, ZnSO ₄ .7H ₂ O as a metal oxide source was dissolved in water by stirring for 1 hour so that [Zn ²⁺ ] was 0.02M. NH ₄ Cl as a complexing agent was stirred in this solution for 30 minutes so that Ra = [NH ⁴⁺ ] / [Zn ²⁺ ] = 30 to prepare a mother liquor having [Zn ²⁺ ] of 0.02M. .
Next, water and an aqueous NaOH solution were added to the obtained mother liquor so that [Zn ²⁺ ] was 0.01 M and pH = 9.5. As described above, a ZnO crystal growth solution was prepared.
Next, as shown in FIG. 2, the substrate was placed in the obtained ZnO crystal growth solution so that the crystal plane on which ZnO was deposited was on the lower side, and immersed at 60 ° C. for 24 hours. Thereafter, the substrate was taken out and dried. The pH of the solution after removing the substrate was 9.41.

The dried ZnO crystal was observed with a field emission scanning electron microscope (SEM) (S-900, manufactured by Hitachi, Ltd.). The SEM photograph at this time is shown in FIGS. 5A is a plan view and FIG. 5B is a side perspective view. 6A is a plan view, and FIG. 6B is a side perspective view. From the SEM photograph, a plurality of hexagonal columns having a bottom surface radius of about 250 to 450 nm are accumulated on the crystal plane of the substrate at intervals. The height of the hexagonal column is 250 to 450 nm, and all the hexagonal columns are aligned.
FIG. 4 shows a diffraction pattern by an X-ray diffractometer (XRD) after zinc oxide is grown on the substrate. From the result of FIG. 4, it is recognized that only the 002 plane of zinc oxide is selectively grown.

(Example 2)
A gallium nitride (GaN) film having a film thickness of 1.5 μm was formed on the c-plane (0001) of the sapphire substrate by MOCVD to produce a GaN film-coated sapphire substrate.
Table 1 shows the lattice constant and misfit rate of this substrate. A diffraction pattern by an X-ray diffractometer (XRD) is shown in FIG. From the result of FIG. 7, it is recognized that the obtained GaN film-coated sapphire substrate is formed of an epitaxial material in which gallium nitride is epitaxially grown on the c-plane (0001) of the sapphire substrate.

Next, crystal growth of zinc oxide (ZnO) was performed in the same manner as in Example 1 using the obtained GaN film-coated sapphire substrate. The pH of the solution after removing the substrate was 9.47.
The dried ZnO crystal was observed with a field emission scanning electron microscope (SEM) (S-900, manufactured by Hitachi, Ltd.). The SEM photograph at this time is shown in FIG.
From the SEM photograph, a hexagonal column with a bottom radius of about 2.3 μm and a height of about 1.2 μm, a hexagonal pyramid with a height of about 20 μm (falling down), standing perpendicular to the substrate, Some were arranged in parallel. Since the fold cross section and the base cross section of the hexagonal column coincide with each other, it is assumed that what was standing vertically during the precipitation growth was broken for some reason (see FIGS. 9B and 9C).
A diffraction pattern by an X-ray diffractometer (XRD) is shown in FIG. From the result of FIG. 8, it is recognized that the 002 plane of zinc oxide is selectively grown.

(Comparative Example 1)
A ZnO sol-gel coated substrate in which ZnO was sol-gel coated on a glass substrate was produced as follows.
First, Zn (CH ₃ COO) ₂ .2H ₂ O was added to 2-methoxyethanol and 2-aminoethanol so that [2-aminoethanol] / [Zn] = 1.0 and stirred for 1 hour. did.
The obtained [Zn ²⁺ ] = 0.75M precursor solution was applied onto a slide glass by spin coating at 3000 rpm for 10 seconds, and heat-treated at 400 ° C. for 15 minutes. Thus, a ZnO sol-gel coated substrate was produced.
Table 1 shows the lattice constant and misfit rate of this substrate. Further, no peak was observed in the diffraction pattern by the X-ray diffractometer (XRD). The cause is considered that the grown ZnO was a crystal, but this film was very thin, or ZnO was amorphous.

  Next, ZnO crystals were grown on the obtained ZnO sol-gel coated substrate in the same manner as in Example 1 except that the reaction time was changed to 6 hours, 12 hours, 24 hours, and 72 hours. The pH of the solution after removing the substrate was 9.45 after 6 hours, 9.45 after 12 hours, 9.42 after 24 hours, and 9.42 after 72 hours.

The dried ZnO crystal was observed with a field emission scanning electron microscope (SEM) (S-900, manufactured by Hitachi, Ltd.). The SEM photograph at this time is shown in FIGS. . FIG. 10A is a plan view after immersion for 12 hours, and FIG. 10B is a side perspective view after immersion for 12 hours. FIG. 11A is a plan view after immersion for 24 hours, and FIG. 11B is a side perspective view after immersion for 24 hours. 12A is a plan view after 72 hours of immersion, and FIG. 12B is a side perspective view after 72 hours of immersion.
From the SEM photograph, hexagonal columns having a bottom radius of about 40 to 60 nm were densely formed on the substrate, and the growth direction was also non-uniform compared to Example 1. The film thickness was 1.4 μm at 6 hours, 1.6 μm at 12 hours, 2.0 μm at 24 hours, and 2.7 μm at 72 hours.
A diffraction pattern obtained by an X-ray diffractometer (XRD) is shown in FIG. From the results of FIG. 13, it is recognized that the peak height increases as the 002 surface of zinc oxide grows selectively and the immersion time becomes longer. However, the peak was weaker than in Examples 1 and 2, and the crystallinity was low.

* As the lattice constant of the ZnO crystal to be grown on the substrate, a ₀ axis = 0.325 nm and c ₀ axis = 0.521 nm were used for misfit calculation.
* Misfit rate (%) = [(A−A ₀ ) / A ₀ ] × 100
However, in said formula, A represents the lattice constant of the a-axis direction of the board | substrate which has a crystal plane containing a metal containing material. A ₀ represents the lattice constant in the a-axis direction of the metal oxide crystal deposited on the crystal plane.

  The metal oxide structure produced by the method for producing a metal oxide structure of the present invention and the metal oxide particles produced by the method for producing metal oxide particles include an insulator, a conductor, a solid electrolyte, and a fluorescent display tube. EL devices, ceramic capacitors, actuators, laser oscillation devices, cold cathode devices, ferroelectric memories, piezoelectric materials, thermistors, varistors, superconductors, printed circuit boards and other electronic materials, electromagnetic shielding materials, photodielectric materials, light Optical elements such as switches, photosensors, solar cells, light wavelength conversion elements, light absorption filters, sensor materials such as temperature sensors and gas sensors, surface modifiers, surface protective agents, antireflection agents, antibacterial, antifouling effects, etc. It can be widely used as a target surface modifier, a catalyst in the gas phase, liquid phase, or both phases, a carrier thereof, and the like.

FIG. 1 is a conceptual diagram showing growth conditions for zinc oxide (ZnO) crystals in Example 1. FIG. FIG. 2 is a schematic view showing how the substrate is immersed in the solution. FIG. 3 is a diffraction pattern obtained by X-ray diffraction measurement of a sapphire substrate. FIG. 4 is a diffraction pattern by X-ray diffraction measurement showing a state in which zinc oxide (ZnO) is deposited on a sapphire substrate. 5A is a SEM photograph of the zinc oxide (ZnO) crystal produced in Example 1. FIG. 5B is a SEM photograph of the zinc oxide (ZnO) crystal produced in Example 1. FIG. 6A is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 1. FIG. 6B is a SEM photograph of the zinc oxide (ZnO) crystal produced in Example 1. FIG. FIG. 7 is a diffraction pattern obtained by X-ray diffraction measurement of a substrate on which a GaN film is formed on sapphire. FIG. 8 is a diffraction pattern obtained by X-ray diffraction measurement showing a state in which ZnO is deposited on a substrate having a GaN film formed on sapphire. FIG. 9A is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 2. FIG. 9B is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 2. FIG. 9C is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 2. FIG. 9D is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 2. FIG. 9E is an SEM photograph of the zinc oxide (ZnO) crystal produced in Example 2. FIG. 10A is a SEM photograph of the zinc oxide (ZnO) crystal produced in Comparative Example 1 after being immersed for 12 hours. FIG. 10B is an SEM photograph of the zinc oxide (ZnO) crystal produced in Comparative Example 1 after being immersed for 12 hours. FIG. 11A is an SEM photograph of the zinc oxide (ZnO) crystal produced in Comparative Example 1 after being immersed for 24 hours. FIG. 11B is a SEM photograph of the zinc oxide (ZnO) crystal produced in Comparative Example 1 after being immersed for 24 hours. 12A is an SEM photograph after 72 hours immersion of the zinc oxide (ZnO) crystal produced in Comparative Example 1. FIG. 12B is a SEM photograph after 72 hours immersion of the zinc oxide (ZnO) crystal produced in Comparative Example 1. FIG. FIG. 13 is a diffraction pattern by X-ray diffraction measurement showing a state in which zinc oxide is deposited on a sol-gel coated ZnO substrate.

Explanation of symbols

1 Substrate (Sapphire single crystal substrate)
2 Metal oxide film (ZnO)
3 Reaction solution 10 Reaction vessel (beaker)

Claims (23)

  A substrate having a crystal plane containing a metal-containing material having a regular crystal orientation structure in a fixed orientation is immersed in a reaction solution capable of depositing a metal oxide, and a metal oxide crystal is formed on the crystal plane containing the metal-containing material. A method for producing a metal oxide structure characterized by depositing a metal.   The method for producing a metal oxide structure according to claim 1, wherein the substrate is disposed so that the crystal plane containing the metal-containing material faces downward and is immersed in the reaction solution.   The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material is formed from at least one of a single crystal material and an epitaxial crystal material.   4. The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material is the same crystal plane as the plane orientation of the substrate having the crystal plane.   The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material is a crystal plane perpendicular to the c-axis direction of the substrate having the crystal plane. When the lattice constant in the a-axis direction of the substrate having a crystal plane containing a metal-containing material is A, and the lattice constant in the a-axis direction of the metal oxide crystal deposited on the crystal plane is A ₀ , The method for producing a metal oxide structure according to any one of claims 1 to 5, wherein a misfit rate is 48% or less.
<Formula 1>
Misfit rate (%) = [(A−A ₀ ) / A ₀ ] × 100   The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material contains a metal oxide.   The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material contains zinc oxide (ZnO). The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material contains sapphire (Al ₂ O ₃ ).   The method for producing a metal oxide structure according to claim 1, wherein the crystal plane containing the metal-containing material contains a metal nitride.   The method for producing a metal oxide structure according to claim 10, wherein the metal nitride is gallium nitride (GaN).   The method for producing a metal oxide structure according to claim 11, wherein the gallium nitride (GaN) is gallium nitride formed by metal organic chemical vapor deposition (MOCVD).   The method for producing a metal oxide structure according to any one of claims 1 to 12, wherein the metal oxide deposited on the crystal plane containing the metal-containing material has a wurtzite crystal.   The method for producing a metal oxide structure according to any one of claims 1 to 13, wherein the metal oxide deposited on the crystal plane containing the metal-containing material is zinc oxide (ZnO).   The method for producing a metal oxide structure according to any one of claims 1 to 14, wherein the reaction solution contains at least one selected from Zn and a salt thereof, a hydroxide of Zn, and a hydrate of Zn. .   The method for producing a metal oxide structure according to any one of claims 1 to 15, wherein a complexing agent is contained in the reaction solution.   A metal oxide structure produced by the method for producing a metal oxide structure according to claim 1, having a metal oxide crystal having an aspect ratio of 1 or more on a substrate.   The metal oxide particle according to claim 17, wherein the metal oxide crystal has any one of a needle shape and a rod shape.   A method for producing metal oxide particles, comprising producing metal oxide particles by separating the metal oxide structure according to any one of claims 17 to 18 from a substrate.   The method for producing metal oxide particles according to claim 19, wherein the separation is performed by cutting the metal oxide crystal deposited on the substrate from the root of the metal oxide crystal.   The method for producing metal oxide particles according to claim 19, wherein the separation is performed by dissolving and removing only the substrate from the substrate on which the metal oxide crystals are deposited.   The metal oxide particles having an aspect ratio larger than 1 produced by the method for producing metal oxide particles according to claim 19. The metal oxide particles according to claim 22, wherein the metal oxide particles have any one of a needle shape and a rod shape.