WO2017138695A1 - Reactor - Google Patents

Abstract

The present application relates to a reactor. The reactor according to the present application suppresses the explosive reaction rate of a metal nanoparticle precursor by spraying a solution comprising a metal precursor to a solution comprising a reactive compound very highly reactive to the metal precursor and thus can control the precursor nanoparticles to have a small particle size even at low costs and accordingly produce a film having uniform surface roughness and a large area.

Description

Reactor

The present application relates to a reactor capable of controlling the reaction rate of a highly reactive compound.

Gallium nitride is a semiconductor material with a wide bandgap energy of 3.4 eV, direct band transitions, high energy radiation and high stability to high temperatures. In view of these properties, gallium nitride is known as a promising material for light emitting diodes, short wavelength lasers, UV detectors and solar cell windows in space.

For example, the gallium nitride film may be mixed with a solution containing a gallium precursor and a solution containing sodium dimethyldithiocarbamate to form metal precursor nanoparticles, followed by coating the nanoparticles on a substrate and performing heat treatment. Although it may be prepared, the gallium precursor and sodium dimethyldithiocarbamate has a very high reactivity, when a simple mixing of the gallium precursor and sodium dimethyldithio carbamate, an explosive reaction occurs. Therefore, a phenomenon in which the metal precursor nanoparticles formed during the reaction may be aggregated may occur. In this case, it may be difficult to control the particle size of the metal precursor nanoparticles evenly, and the base layer may include a solution containing the metal precursor nanoparticles. When coating on, it may be difficult to form a uniform and thin coating layer. Furthermore, in the past, an expensive microchannel reactor was used to control the reaction rate of such a highly reactive compound, but a method of controlling the reaction rate at a lower cost is required.

The present application provides a reactor capable of controlling the reaction rate of a highly reactive compound.

The present application relates to a reactor. According to an exemplary reactor of the present application, by suppressing the explosive reaction rate of the metal nanoparticle precursor by injecting a solution containing the metal precursor to a solution containing a reactive compound having a very high reactivity with the metal precursor, The particle size of the precursor nanoparticles can be controlled to be small, whereby a film having a uniform surface roughness can be produced in a large area.

Hereinafter, with reference to the accompanying drawings will be described a reactor of the present application. The accompanying drawings are illustrative and do not limit the reactor of the present application.

1 exemplarily shows a reactor 100 of the present application.

An exemplary reactor of the present application includes a reaction vessel 120 and a reaction rate controller 110.

The reactor 120 refers to a water tank or a container in which the reaction takes place, and in one example, the reactor 120 may be filled with a solution containing a reactive compound reacting with a metal precursor.

The metal precursor may include one or more selected from the group consisting of metal nitrate, metal acetate, and metal chlorides. In addition, the metal is not particularly limited as long as it is a metal capable of reacting with the reactive compound. For example, the metal may be a metal of Group 8, Group 11, Group 12, or Group 13. In one example, the metal may be at least one selected from the group consisting of gallium, aluminum, indium, thallium, zinc, copper, iron, and tin, and may be, for example, gallium, aluminum, or indium, but is not limited thereto. It doesn't happen. In one example, when the metal is gallium, the metal precursor may be gallium nitrate (Ga (NO ₃ ) _{3 ·} 8H ₂ O), gallium acetate or gallium chloride.

The reactive compound is a compound having a very high reactivity with the metal precursor, the reaction of the metal precursor and the reactive compound may satisfy the following general formula (1).

[Formula 1]

Rp ≥ 1 μm / min

In Formula 1, Rp represents a rate of increase in particle size that is a reactant of the metal precursor and a reactive compound within Ts time,

The Ts represents the time when the growth of the particle size is saturated.

2 is a graph illustrating a change in particle size or diameter according to a reaction time.

For example, as shown in FIG. 2, depending on the reaction time, the particle size may change in the form of a quadratic function. As shown in FIG. 2, the point of time corresponding to the boundary between the area where the particle size grows explosively according to the reaction time and the area where the particle size grows slowly according to the reaction time, that is, the time that the growth of the particle size saturates is Ts. For example, Ts is the time at the point where the first straight line of the graph meets the first straight line of the graph during the time that the particle size grows in the graph of FIG. It may mean. For example, in the left region of the Ts time of FIG. 2, depending on the reaction time, the particle size grows explosively, for example, the rate of increase of the particle size in the left region of the Ts time may be 1 μm / min or more. . In addition, in the right region of the Ts time of FIG. 2, the growth of the particle size does not occur or grows at a very low rate depending on the reaction time, for example, the increase rate of the particle size in the right region of the Ts time is 1 μm / min. May be less than.

When the reaction of the metal precursor and the reactive compound satisfies the general formula 1, that is, within the Ts time, when the rate of increase in particle size that is a reactant of the metal precursor and the reactive compound is 1 μm / min or more, By effectively suppressing the explosive reaction rate of the metal nanoparticle precursor by using the reactor 100 of the application, it is possible to control the particle size of the precursor nanoparticles at a low cost, thereby having a uniform surface roughness Films can be produced in large areas.

In one example, the reactive compound may be a compound represented by Formula 1 below.

[Formula 1]

In Chemical Formula 1,

M ₁ is a Group 1 metal,

R ₁ and R ₂ each independently represent alkyl having 1 to 12 carbon atoms.

For example, M ₁ may be a Group 1 alkali metal, such as lithium, sodium or potassium, and in one example may be sodium.

In addition, each of R ₁ and R ₂ may be independently an alkyl group having 1 to 12 carbon atoms, for example, 1 to 8 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. For example, R ₁ and R ₂ may be each independently methyl, ethyl, propyl, butyl, pentyl or hexyl, and in one example may be methyl, but is not limited thereto.

In one example, the compound of Formula 1 may be sodium dimethyldithiocarbamate (CH ₃ ) ₂ NCSSNa.2H ₂ O), the solution containing the reactive compound is sodium dimethyldithiocarba Mate.

The first solvent in which the compound of Formula 1 is dissolved is selected from the group consisting of alcohol (C _n H _{2n + 1} OH, ₁ ≦ _n ≦ 6) solvent, such as methanol, 2-methoxyoxyethanol, ethanol, and water. It may be more than, for example, may be methanol, but is not limited thereto.

The reaction rate control unit 110 is a device that controls the reaction rate of the metal precursor and the reactive compound occurring in the reaction tank 120. As described above, when the metal precursor has a very high reaction rate with a reactive compound such as the compound of Formula 1, when the first solution and the second solution are simply mixed, an explosive reaction occurs. Therefore, aggregation of the formed metal precursor nanoparticles may occur. In this case, it is difficult to evenly control the particle size of the metal precursor nanoparticles, and the solution containing the metal precursor nanoparticles may be coated on the substrate layer. In this case, it may be difficult to form a uniform and thin coating layer. Accordingly, in the reactor of the present application, by spraying and mixing the solution containing the metal precursor to the solution containing the reactive compound by the reaction rate control unit, the metal precursor nanoparticles are highly dispersed in the mixed solution to precipitate, thereby Accordingly, it is possible to form metal precursor nanoparticles controlled to have a particle size distribution (PSD) with a small average particle diameter and a very small standard deviation. Furthermore, in the past, an expensive microchannel reactor was used to control the reaction rate of such highly reactive compounds. However, according to the reactor of the present application, by controlling the reaction rate using the injection device 110, There is an advantage that can control the reaction rate at low cost.

In one embodiment, the solution comprising the metal precursor and the solution comprising the reactive compound may be mixed by a spray device 100, in one example, the solution comprising the metal precursor is The mixed solution may be prepared by spraying on a solution containing a reactive compound.

The first solvent in which the metal precursor is dissolved may be at least one selected from the group consisting of an alcohol (C _n H _{2n + 1} OH, ₁ ≦ _n ≦ 6) solvent, such as _2- methoxyoxyethanol, methanol, and ethanol, and water. For example, it may be methanol, but is not limited thereto.

The spraying apparatus 100 may be an ultrasonic vibration spraying apparatus, an electro spraying apparatus, or a plasma spraying apparatus. For example, as shown in FIG. 1, a spray header equipped with an ultrasonic vibration generator is provided. Or using an electrospray. In this case, the spraying may be performed to spray at a flow rate of 20 ml / hr or less, for example, 15 ml / hr or less or 10 ml / hr or less.

The solution containing the metal precursor and the solution containing the reactive compound may be mixed to prepare a mixed solution. In the mixed solution, metal precursor nanoparticles of the following Chemical Formula 2 may be formed by a reaction between a metal precursor in a solution including the metal precursor and a reactive compound in a solution including the reactive compound, for example, the compound of Formula 1. Can be. Accordingly, the mixed solution may include the metal precursor nanoparticles of Formula 2, and may further include a first solvent included in the solution including the metal precursor and the solution including the reactive compound.

[Formula 2]

In Formula 2, M ₂ may be a metal of Group 8, Group 11, Group 12 or Group 13, for example, aluminum, gallium, indium, thallium, zinc, copper, iron or tin, in one example It can be gallium.

In addition, each of R ₃ and R ₄ may be independently an alkyl group having 1 to 12 carbon atoms, for example, 1 to 8 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. For example, each of R ₃ and R ₄ may be independently methyl, ethyl, propyl, butyl, pentyl or hexyl, and may be methyl in one example, but is not limited thereto.

In one example, the compound of Formula 2 is tris (N, N-dimethyldithiocarbamate) -gallium (III) (Tris (N, N-dimethyldithiocarbamato) -gallium (III), Ga (DmDTC) ₃ ), Wherein the third solution may comprise tris (N, N-dimethyldithiocarbamate) -gallium (III), preferably, the residual sodium dimethyldithio contained in the second solution Carbamate and the tris (N, N-dimethyldithiocarbamate) -gallium (III).

 In one example, the average particle diameter of the metal precursor nanoparticles of Formula 2 may be 5 to 100 nm, for example, 10 to 70 nm, or 15 to 50 nm, preferably 20 to 40 nm. . In addition, the particle size distribution of the metal precursor nanoparticles of Formula 2 has a very small standard deviation, and in one example, the particle size distribution of the metal precursor nanoparticles is 5 to 40 nm, for example, It can have a standard deviation of 10 to 30 nm, 10 to 20 nm.

The metal precursor nanoparticles of Formula 2 having the average particle diameter and particle size distribution as described above may be obtained from the mixed solution. For example, the first solvent of the mixed solution may be evaporated or centrifuged to obtain the metal precursor nanoparticles of Chemical Formula 2. The obtained metal precursor nanoparticles may be washed with deionized water, and the washed metal precursor nanoparticles may be dried at a temperature of 50 ° C. or higher for at least 4 hours.

Another embodiment of the present application relates to a method of manufacturing a metal nitride film using the metal precursor nanoparticles of the formula (2) obtained in the reactor.

In one example, the obtained metal precursor nanoparticles of the formula (2) may be dissolved in a second solvent, the metal precursor nanoparticle solution prepared according to may include the metal precursor nanoparticles of the formula (2).

After the solution is prepared, the metal precursor nanoparticle solution including the metal precursor nanoparticles may be coated on the substrate layer.

The coating may be performed through various coating methods known in the art, for example, but not limited to spray coating, spin coating, screen printing or dip coating.

As described above, the prepared metal precursor nanoparticles have a very small average particle diameter and a narrow range of particle size distribution, and accordingly, since the metal precursor nanoparticles have a uniform and small particle diameter, the coating layer of the metal precursor nanoparticle solution is It can have a very thin thickness and a uniform thickness.

The coating layer of the metal precursor nanoparticle solution may be formed to have a thickness of 15 μm or less, and the metal nitride layer formed after the heat treatment to be described later may have a thickness of 10 μm or less.

In the metal precursor nanoparticle solution, the second solvent for dispersing the metal precursor nanoparticles of Chemical Formula 2 may be used without limitation as long as it is a highly evaporative solvent. For example, chloroform (CH ₃ Cl), methanol, It may be at least one selected from the group consisting of ethanol and ether, and in one example, may be chloroform, but is not limited thereto.

The metal precursor nanoparticle solution layer coated on the substrate layer may be heat treated under a nitrogen gas or ammonia gas atmosphere, and by the heat treatment, the sulfur atom of the compound of Formula 2 in the metal precursor nanoparticle solution layer is nitrogen gas or ammonia It may be substituted with a nitrogen atom of the gas. Accordingly, a film including a metal nitride layer having a final thin thickness and a uniform thickness can be manufactured.

3 is a diagram illustrating an apparatus 200 in which a heat treatment is performed in the manufacturing method of the present application.

As shown in FIG. 3, the apparatus 200 includes a furnace 210 and a tube 220, and the heat treatment may be performed in a furnace and a tube. The heating furnace may include a heating means 211, and the heating means 211 may be positioned while surrounding the tube 220 to heat the tube formed through the heating furnace 210. The tube 220 may be, for example, a quartz tube. The support means 300 for fixing the base layer 11 coated with the metal precursor nanoparticle solution may be located inside the quartz tube 220, and the inside of the quartz tube may be maintained in a nitrogen or ammonia atmosphere. have.

In one example, the heat treatment may be performed at a temperature of 300 ℃ to 1200 ℃, for example, may be performed at a temperature of 500 ℃ to 1100 ℃, 600 to 1000 ℃ or 800 to 900 ℃, but is not limited thereto. It doesn't happen. In addition, the heat treatment may be performed for 5 minutes to 60 minutes, for example, 10 minutes to 50 minutes, or 15 minutes to 30 minutes, but is not limited thereto.

In one example, the metal nitride layer formed by the heat treatment of the metal precursor nanoparticle solution layer including the metal precursor nanoparticles of Formula 2 may be formed according to the following schemes 1 and 2.

Scheme 1

2Ga (S ₂ CN (CH ₃ ) ₂ ) ₃ → 2Ga ₂ S ₃ + adducts

Scheme 2

Ga ₂ S ₃ + 2NH ₃ → 2GAN + 3H ₂ S

The present application also relates to a film produced by the above-described manufacturing method. Exemplary film of the present application, as prepared using the metal precursor nanoparticles obtained by the reactor of the present application described above, comprises a very thin and uniform thickness of the metal nitride layer of several micrometers, and also, Sulfur atoms in the metal precursor nanoparticles of doped the metal nitride layer, the sulfur component on the surface has a feature that is detected in the photoluminescence (PL) spectrum.

Hereinafter, with reference to the accompanying drawings will be described a film of the present application. The accompanying drawings are illustrative and do not limit the films of the present application.

4 is a cross-sectional view schematically showing a film of the present application.

As shown in FIG. 4, the film 10 of the present application includes a base layer 11 and a metal nitride layer 12 formed on at least one surface of the base layer 11.

In the metal nitride layer 12, the photoluminescence (PL) spectrum measured using a laser of 325 nm wavelength satisfies the following general formula (2).

[Formula 2]

E (I _max ) = E _g -0.1 × k

In the general formula 2,

E (I _max ) represents the bandgap energy at the position having the maximum intensity value of the photoluminescence spectrum,

Eg represents the bandgap energy of the metal nitride,

k is a rational number greater than 2 and less than six.

The term "photoluminescence" refers to a phenomenon in which a material is stimulated by light to emit light by itself, and more specifically, when an electron in a light-absorbing material becomes excited and then returns to its original state. It means the phenomenon of emitting light. Photoluminescence (PL) Spectrum is a spectrum showing the relative intensity representing the energy-specific distribution of light emitted from a material irradiated with light by using light luminescence. The intensity of the photoluminescence spectrum has a maximum intensity value (hereinafter, referred to as a peak value) in an energy band unique to a material. Since the intensity value of the photoluminescence spectrum is a relative value, it is expressed in units of a.u. (arbitrary unit).

The PL measurement may be performed using a He-Cd laser having a center wavelength of 325 nm for the excitation light source. The measurement temperature is not particularly limited, but it is preferable to perform the measurement at 20 K or lower. Examples of the device capable of measuring PL under such conditions include Omnichrome series 74 He-Cd laser, Acton SpectraPro 2300i spectrometer, Princeton Instruments PI-MAX1024HQ-Blu CCD detector, and the like. On the other hand, when there is a defect in the film formed during the PL measurement, there is a case where the PL spectrum of sufficient intensity cannot be obtained and cannot be evaluated at room temperature. In such a case, the PL spectrum signal can be easily detected by using a low temperature PL of 20 K or less.

As described above, the metal nitride layer 12 may be formed by replacing sulfur atoms in the metal precursor nanoparticles of Chemical Formula 2 with nitrogen atoms when heat-treating the coating layer including the metal precursor nanoparticles of Chemical Formula 2. In this case, sulfur atoms in the metal precursor nanoparticles of Chemical Formula 2 are doped into some metal nitride layers 12, and sulfur components are detected in a photoluminescence (PL) spectrum on the surface. Accordingly, in the metal nitride layer 12, the photoluminescence (PL) spectrum measured using a laser of 325 nm wavelength satisfies the general formula (2).

In one example, when the metal nitride layer is a gallium nitride layer, the metal nitride layer satisfying Formula 2 has a maximum intensity value of the photoluminescence (PL) measured using a laser of 325 nm wavelength of 2.8 to It will be in the range of 3.2 eV. This is because, as described above, sulfur atoms in the metal precursor nanoparticles of Chemical Formula 2 are doped into some metal nitride layers 12 so that sulfur components are detected in the photoluminescence (PL) spectrum at the surface.

For example, in the case of the gallium nitride layer, as shown in Fig. 8, the bandgap energy at the position having the maximum intensity value of the photoluminescence spectrum represented by the sulfur component is 2.95 eV, and the bandgap energy of gallium nitride is 3.44 eV. Therefore, k value calculated according to the general formula (2) is 4.9, thereby satisfying the general formula (2).

The sulfur component detected on the surface of the metal nitride layer 12 may also be confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The metal nitride layer 12 may include Mg after removing a surface oxide layer with an ion gun using an inert gas. The maximum intensity value of the XPS spectrum measured on the basis of Kα X-ray may be in the range of 160.0 eV to 170.0 eV. For example, in the metal nitride layer, the maximum intensity value of the XPS spectrum can be found around about 164 eV (based on the carbon 1s peak of 284.5 eV, sulfur 2p3 / 2 peak). In addition, it can be confirmed that it contains sulfur within 5% by weight through quantitative analysis through XPS.

The "XPS analysis" is a method of using X-rays as a light source in electron spectroscopy, and when X-rays are irradiated to a substance, photoelectrons are emitted out of the substance, and the kinetic energy is at an original position under the cabinet electrons of the atoms constituting the substance. Since it reflects the magnitude of the binding force, this means a method of investigating the atomic composition of a material and the bonding state of electrons.

As described above, the metal nitride layer 12 of the present application may have a very even thickness, and in one example, the metal nitride layer 12 may be 5-10 nm, for example, 6-9 nm, It may have a centerline average roughness of 6 to 8 nm or 7 to 8 nm.

In the above description, the center line average roughness is extracted by the reference length L in the direction of the average line from the roughness curve, the average line direction of the extracted portion is X-axis, and the height direction is Y-axis, and the roughness curve is a function y = f (x When it is expressed by) means that the value can be obtained by the following equation (1) expressed in micrometer (μm) or nanometer (nm). The center line average roughness is measured under the standard of JIS B0031, JIS B0601 or ISO 468.

[Equation 1]

In one example, the metal may be one or more selected from the group consisting of gallium, aluminum, indium and lead, for example, gallium, but is not limited thereto.

The base layer 11 may have a melting point of 300 ° C. or higher. When the melting point of the base layer 11 is less than 300 ° C., the components of the base layer may melt during the heat treatment process, and thus carbon or carbon-related byproducts may remain in the metal nitride layer. The substrate layer 11 may include at least one polymer substrate selected from the group consisting of acrylonitrile, polyphenylenevinylene, polytetrafluoroethylene, polyvinylcarbazole, and polyimide, or The layer 11 may include one or more selected from the group consisting of alumina, silicon carbide (SiC), silicon, quartz, glass, and stainless steel. In one example, the base layer 11 may be alumina. However, it is not limited thereto.

As described above, the metal nitride layer 12 may be formed to have a very thin thickness. In one example, the thickness of the metal nitride layer 12 may be 10 μm or less, for example, 8 μm or less, or 5 μm or less, but is not limited thereto.

In one example, metal nitride layer 12 may include a crystalline phase and an amorphous phase.

According to the reactor of the present application, by spraying a solution containing the metal precursor to a solution containing a reactive compound having a very high reactivity with the metal precursor to suppress the explosive reaction rate of the metal nanoparticle precursor, the precursor nano at a low cost The particle size of the particles can be controlled small, whereby a film having a uniform surface roughness can be produced in a large area.

1 exemplarily shows a reactor of the present application.

2 is a graph showing the change in particle size with reaction time.

3 exemplarily shows an apparatus in which a heat treatment is performed in the method of the present application.

4 is a cross-sectional view schematically showing a film of the present application.

(A) of FIG. 5 Ga (DmDTC) and ¹ H-NMR spectrum of the nanoparticles _3, (b) of Figure 5 is a graph and a photograph showing the size distribution and shape of Ga (DmDTC) ₃ nanoparticles.

FIG. 6A is an XRD pattern of a gallium nitride layer by pyrolytic deformation of Ga (DmDTC) ₃ film in an environment where ammonia flows, and FIG. 6B is an SEM photograph of the surface and cross section of the gallium nitride layer. .

FIG. 7 is a graph illustrating a pyrolysis reaction of Ga (mDTC) ₃ using a thermogravimetric analyzer.

8 shows a high resolution XP spectrum of the Ga 2p _3/2 , N 1s and O 1s peaks.

9 shows the PL spectrum of a gallium nitride layer at room temperature.

FIG. 10 shows XRD patterns and SEM photographs of epitaxial gallium nitride films grown on gallium nitride layers pyrolyzed by MOCVD.

11 is an image taken using a scanning electron microscope (Scanning Electron Microscope, SEM) of the gallium nitride thin film prepared in Comparative Example.

<Description of the code>

10: film

11: base layer

12: metal nitride layer

100: reactor

110: reaction rate control

120: reactor

200: heat treatment device

210: heating furnace

211: heating means

220: quartz tube

300: support means

Hereinafter, the above-described contents will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present application is not limited by the contents given below.

Physical properties in the following Examples and Comparative Examples were measured using the following methods and apparatus.

Identification of Synthesized Metal Precursor Nanoparticles

Metal precursors synthesized in the following examples and comparative examples Nanoparticles were identified using a ¹ H-Fourier transform magnetic resonance system ( ¹ H-FT-NMR, Bruker DPX300).

Size Measurement of Synthesized Metal Precursor Nanoparticles

Metal precursors synthesized in the following examples and comparative examples The size of nanoparticles is not only measured by transmission electron microscope (TEM, Hitachi, H-7600) and X-ray diffraction (X-ray diffraction, XRD, PANalytical, X'pert PRO), but also by particle size analyzer (Beckman Coulter, N5).

Measurement of the structure and morphological properties of the metal nitride layer

The structure and morphological properties of the metal nitride layers formed in the following Examples and Comparative Examples were measured using a scanning electron microscope (Scanning Electron microscopy, SEM, Hitachi, S-4100).

Measurement of optoelectronic properties of metal nitride layers

The optoelectronic physical properties of the metal nitride layers formed in the following Examples and Comparative Examples were measured by photoluminescence spectroscopy (PL) using a He-Cd laser at a wavelength of 325 nm.

Measurement of compositional ratio and bonding of metal nitride layer

The compositional ratio and bonding of the metal nitride layers formed in the following Examples and Comparative Examples were measured by X-ray photoemission spectroscopy (XPS, VG Microtech, MT 500/1).

Determination of Centerline Average Roughness of Metal Nitride Layers

The center line average roughness of the metal nitride layers formed in the following Examples and Comparative Examples was calculated using Equation 1 based on the height data obtained at this time by scanning the surface using an atomic force microscope (AFM).

Example 1

In the following manner, a gallium nitride layer was formed on the alumina base layer.

As a precursor of the gallium nitride layer as shown in FIG. 1, tris (N, N-dimethyldithiocarbamate) -gallium (III) (Ga (S ₂ CN (CH ₃ ) ₂ ) ₃ , Ga (DmDTC) ₃ ) Nanoparticles were synthesized using ultrasonic spraying.

First, gallium nitrate (Ga (NO ₃ ) .8H ₂ O) in 50 ml of methanol and sodium dimethyldithiocarbamate ((CH ₃ ) in 20 ml of methanol, so that the molar ratio of gallium salt to sodium salt makes 1.3. ₂ NCSSN _a · 2H ₂ O) were prepared separately.

The gallium nitrate solution was ultrasonically sprayed on the sodium dimethyldithiocarbamate ligand solution for 30 minutes at room temperature, and the flow rate of the gallium nitrate solution was maintained at 10 ml / hr during the spraying process. The Ga (DmDTC) ₃ nanoparticles were synthesized by a very slow sedimentation process, and the precipitated material was filtered using a centrifugation process. The synthesized Ga (DmDTC) ₃ nanoparticles were washed several times with deionized water and dried in a vacuum oven at 60 ° C. for 4 hours. The average diameter of the prepared Ga (DmDTC) ₃ nanoparticles was measured as 28.5 nm, the standard deviation of the particle size distribution of the produced Ga (DmDTC) ₃ nanoparticles was measured to be 13.3 nm. The Ga (DmDTC) ₃ nanoparticles were dispersed by ultrasonic in the chemical chloroform (CHCl ₃₎ solvent at room temperature for 1 hour.

The Ga (DmDTC) ₃ nanoparticles dispersed solution was spin-coated on a c-axis alumina substrate (1 cm x 1 cm) at 2000 rpm for 30 seconds, dried at room temperature for 10 minutes, and then repeated 5 times. to form a film having a thickness of Ga (DmDTC) ₃ 5 ㎛. Thereafter, using the apparatus of FIG. 2, Ga (DmDTC) ₃ as formed above. The film was heat-treated at 850 ° C. for 10 minutes in an ammonia (NH ₃ ) atmosphere having a flow rate of 170 sccm. After the pyrolysis process, the sample was cooled to room temperature under a nitrogen atmosphere, and gallium nitride having a thickness of 5 μm on the alumina base layer. A layered film was prepared. In this case, the centerline surface roughness of the gallium nitride layer was measured to be 7 nm.

Thereafter, the gallium nitride film was epitaxially grown on the prepared gallium nitride layer by MOCVD. At this time, the deposition time was maintained for 5 minutes to test the initial growth of the gallium nitride film, the thickness of the deposited epitaxial gallium nitride film was 500 nm.

Example 2

A film in which an aluminum nitride layer having a thickness of 5 μm was formed on the alumina base layer in the same manner as in Example 1, except that aluminum nitrate was used as the metal precursor. In this case, the centerline surface roughness of the aluminum nitride layer was measured to be 7 nm.

In this case, the average particle diameter of the produced Al (DmDTC) ₃ nanoparticles was measured as 20 nm, the standard deviation of the particle size distribution of the produced Al (DmDTC) ₃ nanoparticles was measured to be 5 nm.

Example 3

A film in which an indium nitride layer having a thickness of 5 μm was formed on the alumina base layer in the same manner as in Example 1, except that indium nitrate was used as the metal precursor.

The standard deviation in this case, the average particle size of the prepared In (DmDTC) ₃ nanoparticles was measured as 30 nm, prepared In (DmDTC) of ₃ nanoparticle particle size distribution is measured by 3 nm. In addition, the centerline surface roughness of the indium nitride layer was measured to be 9 nm.

Example 4

A film in which an indium nitride layer having a thickness of 5 μm was formed on the alumina base layer in the same manner as in Example, except that indium chloride was used as the metal precursor.

In this case, the average particle size of the prepared In (DmDTC) ₃ nanoparticles was measured as 35 nm, the standard deviation of the particle size distribution of the produced In (DmDTC) ₃ nanoparticles was measured to be 5 nm. In addition, the centerline surface roughness of the indium nitride layer was measured to be 10 nm.

Comparative example

Ga (DmDTC) ₃ nanoparticles were formed in the same manner as in Example 1, except that the gallium nitrate solution was not ultrasonically sprayed on the sodium dimethyldithiocarbamate ligand solution, but was simply mixed. To produce a gallium nitride thin film. 10 is an image taken using a scanning electron microscope (Scanning Electron Microscope, SEM) of the gallium nitride thin film prepared in Comparative Example. As shown in FIG. 10, the manufactured gallium nitride thin film did not form a continuous thin film form, and it was very difficult to form a 5 μm thick layer, and showed a very nonuniform and irregular porous structure. Accordingly, the surface roughness of the gallium nitride thin film could not be calculated according to Equation 1 above.

In addition, the average particle diameter of the Ga (DmDTC) ₃ nanoparticles prepared above has a value of about 0.1 to 0.5um, and the standard deviation of the particle diameters of the formed nanoparticles was about 0.1 μm.

Figure 5 (a) shows the ¹ H-NMR spectrum of the Ga (DmDTC) ₃ nanoparticles. The spectra show four peaks of 0 ppm, 1.55 ppm, 3.40 ppm and 7.26 ppm, respectively, assigned to tetramethylsilane (TMS), water in CDCl ₃ , Ga (DmDTC) ₃ and CHCl ₃ in CDCl ₃ . It was. Tetramethylsilane was used as an internal reference for chemical shift calibration, and the peak of singlet at 3.40 ppm is closely related to the chemical shift of Ga (DmDTC) ₃ material. Figure 5 (b) is a graph and photograph showing the size distribution and shape of the Ga (DmDTC) ₃ nanoparticles. As shown in FIG. 5B, the Ga (DmDTC) ₃ nanoparticles synthesized by the ultrasonic spraying method are well monodispersed to have an average particle size of 28.5 nm and a standard deviation of 13.3 nm. Appeared. Generally, the settling reactions of gallium nitrate (Ga (NO ₃ ) .8H ₂ O) and sodium dimethyldithiocarbamate ((CH ₃ ) ₂ NCSSNA.2H ₂ O) take place very quickly, which leads to the control of particle size. This means that it is relatively difficult. In contrast, the ultrasonic spraying method is a useful method for controlling the reaction rate, since the size of the plurality of gallium precursor particles in the ultrasonically sprayed droplets is relatively small. Thus, abrupt reactions to form large particles are effectively prevented, and Ga (DmDTC) ₃ nanoparticles are easily dispersed in chloroform solvent.

FIG. 6 (a) shows the XRD pattern of the gallium nitride layer by pyrolytic deformation of Ga (DmDTC) ₃ film in an ammonia flowing environment. The XRD peaks of the gallium nitride layer are mainly observed at 34.6 ° and 73.1 ° 2θ and are assigned contributing from the (0002) and (0004) planes of the hexagonal structure phase. In addition, no peak attributable to the γ-Ga ₂ S ₃ phase was observed in the XRD pattern. The Ga (DmDTC) ₃ phase turns into a γ-Ga ₂ S ₃ phase under a nitrogen environment above 500 ° C., which indicates that Ga (DmDTC) ₃ is thermally decomposed into adducts of γ-Ga ₂ S ₃ and CN (CH ₃ ). It is known to represent. Thus, the pyrolysis reaction from Ga (DmDTC) ₃ to gallium nitride layer under ammonia can be simply expressed by the thermal decomposition of Ga (DmDTC) ₃ and the chemical reaction between γ-Ga ₂ S ₃ and ammonia. This reaction can be summarized as in Schemes 1 and 2.

Scheme 1

2Ga (S ₂ CN (CH ₃ ) ₂ ) ₃ → 2Ga ₂ S ₃ + adducts

Scheme 2

Ga ₂ S ₃ + 2NH ₃ → 2GAN + 3H ₂ S

The reason why the pyrolyzed gallium nitride layer is well arranged in the culture direction first is expected from the recrystallization process during the pyrolysis reaction. As shown in Schemes 1 and 2, the deposited Ga (DmDTC) ₃ film was changed to Ga ₂ S ₃ by pyrolysis, and the sulfur (S) component was simultaneously replaced with a nitrogen (N) component. At this time, the pyrolyzed gallium nitride layer undergoes a recrystallization process, and because of the low surface energy of the (0002) plane in the hexagonal structure, the crystalline structure of gallium nitride is mainly arranged in the (0002) first culture direction. Furthermore, the gentle slope observed in the XRD pattern confirms the presence of an amorphous phase in the gallium nitride layer. 6 (b) shows SEM images of the surface and cross section of the gallium nitride layer, showing a dense structure and a small crystalline phase. Although the gallium nitride layer was 5 mu m thick, it did not show any voids or cracks. From this, it can be seen that the amorphous phase plays a major role in reducing the lattice mismatch between the gallium nitride layer and the alumina substrate. The reason why the amorphous phase appears in the pyrolyzed gallium nitride layer can be explained as follows. Grain boundaries usually have an amorphous phase, and the crystal structure of the gallium nitride layer terminates at the grain boundaries. Also, nitrogen and sulfur have different oxidation numbers, which means that the sulfur bonds in gallium nitride have modified the crystalline structure of gallium nitride. These can lead to crystalline disorders and defects in the film.

On the other hand, it was observed for the thermal decomposition reaction under conditions to prepare the manufactured Ga (mDTC) ₃ separately, and its temperature is raised to 900 ℃ In order to examine the thermal decomposition of Ga (mDTC) _3. FIG. 7 is a graph illustrating a pyrolysis reaction of Ga (mDTC) ₃ using a thermogravimetric analyzer. As can be seen from Figure 7, in the case of Ga (mDTC) ₃ of the present application, it can be seen that it is completely pyrolyzed at 300 ° C lower than the decomposition temperature of the conventionally known Ga (mDTC) ₃ 500 ° C. This is because, as described above, the smaller the size of the Ga (DmDTC) ₃ nanoparticles, the larger the surface area and thus the lower the decomposition temperature.

8 is Ga 2p _3/2, represents a high-resolution XP spectrum of the N 1s and O 1s peak. The Ga 2p _3/2 deconvolution of peaks (peak deconvoluted) of was observed at 1118.3 eV and 1120.8 eV which apparently moving from the core levels of 1116.5 to 1116.7 eV of gallium. From this, apparent movement of the Ga 2p _3/2 it can be seen that the point has been mixed with the gallium atoms are nitrogen and oxygen in the film. The peak region 1120.8 eV due to oxygen mixing was very small compared to the peak region 1118.3 eV due to nitrogen mixing, indicating that oxygen contamination is sufficiently low in non-vacuum methods. The deconvoluted peaks of N 1s were located at 396.6 eV and 397.7 eV resulting from Ga-N and Ga-S bonds, respectively. The elemental ratio of N to Ga was 1: 0.9 and sulfur was detected in a very small amount in the XPS spectrum. This indicates that almost all of the sulfur atoms in Ga ₂ S ₃ have been replaced with nitrogen atoms, as demonstrated in Scheme 2 above, and the remaining sulfur atoms are used to form sulfur-doped GaN (GaN: S) in an ammonia environment. It is displayed. Peaks of O 1s were observed at 530.8 and 531.8 eV, respectively. In general, oxygen peaks range from 529 to 535 eV, and peaks near 529 to 530 eV represent lattice oxygen, while peaks of 530 to 535 eV are related to carbon uptake or contamination by organic material on the film surface. do. In this case, the O 1s XPS peaks at 530.8 eV and 531.8 eV are assigned to the chemisorption of the film surface.

9 shows the PL spectrum of a gallium nitride layer at room temperature. Three distinct peaks were observed, mainly at 3.44 eV, 2.95 eV and 2.69 eV, respectively. The peak at 3.44 eV is assigned to the band edge transition of gallium nitride. Blue luminescence (BL), concentrated at 2.95 eV, was stronger than the other two peaks, which resulted in the formation of shallow donor levels due to sulfur (S) on the nitrogen (N) site of the gallium nitride layer. Can be considered. As described above in the XPS results, a small amount of sulfur (S) remains in gallium nitride during pyrolysis, and shallow donor levels may be formed due to the substitution of sulfur (S) at the nitrogen (N) site in gallium nitride. have. In general, Group 4 on gallium (Ga) sites and Group 6 on nitrogen (N) sites are considered shallow donors in gallium nitride. Thus, the appearance of these peaks results from the transition from shallow donors to shallow acceptors. Green luminescence (GL) at 2.69 eV results from different charge states of defects due to gallium vacancies and oxygen substitution of nitrogen sites. As a result, the weak band edge emission and the appearance of the BL-GL band are explained by various defects due to abundant gallium, nitrogen depletion and sulfur substitution in the gallium nitride layer, as well as many pathways of many disordered and non-radioactive remixes. Can be.

FIG. 10 shows XRD patterns and SEM photographs of epitaxial gallium nitride films grown on gallium nitride layers pyrolyzed by MOCVD. Then, epitaxial growth of gallium nitride proceeds according to the following schemes (3) and (4).

Scheme 3

Ga (CH ₃ ) ₃ (g) + HCl (g) → GaCl (g) + CH _x group (g)

Scheme 4

_{GaCl (g) + NH 3 (} g) → GaN (s) + HCl (g) + H 2 (g)

The epitaxial gallium nitride film on the pyrolyzed gallium nitride layer exhibited a strong preferred orientation direction in the (0002) direction, resulting from a hexagonal Wurtzite structure. In addition, the grown gallium nitride film showed lateral growth on the substrate, while the gallium nitride film on the bare sapphire substrate grew upward in the z-axis direction. From this, it can be seen that the adsorption atoms were strongly mixed due to the single-epitaxial physical properties between the pyrolyzed gallium nitride layer and the grown gallium nitride.

Claims (7)

A reactor filled with a solution containing a reactive compound reacting with the metal precursor; And a reaction rate control unit controlling a reaction rate of the metal precursor and the reactive compound occurring in the reactor. Reaction of the metal precursor and the reactive compound is a reactor that satisfies the following general formula (1): [Formula 1] Rp≥ 1 μm / min In Formula 1, Rp represents a rate of increase in particle size that is a reactant of the metal precursor and a reactive compound within Ts time, The Ts represents the time when the growth of the particle size is saturated. The reactor according to claim 1, wherein the reaction rate controller is an injection device in which a solution containing a metal precursor is injected. The reactor according to claim 2, wherein the injection device is an ultrasonic vibration injection device, an electric injection device or a plasma injection device. The reactor of claim 2, wherein the injection device comprises a nozzle to which a solution containing a metal precursor is injected and a spraying controller to control the injection speed of the solution. The reactor of claim 1 wherein the metal precursor comprises at least one selected from the group consisting of metal nitrate, metal acetate, and metal chloride. The reactor of claim 1 wherein the metal comprises at least one selected from the group consisting of gallium, aluminum, indium, thallium, zinc, copper, iron and tin. The reactor of claim 1, wherein the reactive compound is a compound represented by Formula 1 below: [Formula 1]

In Chemical Formula 1, M ₁ is a Group 1 metal, R ₁ and R ₄ each independently represent alkyl having 1 to 12 carbon atoms.

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