KR101840534B1

KR101840534B1 - Reactor

Info

Publication number: KR101840534B1
Application number: KR1020160016377A
Authority: KR
Inventors: 박진호; 김홍탁
Original assignee: 영남대학교 산학협력단
Priority date: 2016-02-12
Filing date: 2016-02-12
Publication date: 2018-05-04
Also published as: WO2017138695A1; KR20170094979A

Abstract

According to the reactor of the present application, the solution containing the metal precursor is injected into a solution containing a reactive compound having a very high reactivity with the metal precursor to suppress the explosion reaction rate of the metal nanoparticle precursor , The particle size of the precursor nanoparticles can be controlled to be small even at a small cost, and thus a film having a uniform surface roughness can be produced in a large area.

Description

Reactor {REACTOR}

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

Gallium nitride is a semiconductor material with a wide band gap energy of 3.4 eV, direct band transfer, high energy radiation and high stability to high temperatures. Given 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 formed by mixing a solution containing a gallium precursor and a solution containing sodium dimethyldithiocarbamate to form metal precursor nanoparticles, then coating the nanoparticles on the substrate and heat-treating However, since the gallium precursor and sodium dimethyldithiocarbamate have very high reactivity, an explosive reaction occurs when the gallium precursor and sodium dimethyldithiocarbamate are simply mixed. Therefore, the metal precursor nanoparticles formed during the reaction may be aggregated. In this case, it is difficult to uniformly control the particle size of the metal precursor nanoparticles, and a solution containing the metal precursor nanoparticles is formed on the substrate layer It may be difficult to form a uniform and thin coating layer. Further, in order to control the reaction rate of such a highly reactive compound, an expensive microchannel reactor has been used, but a method of controlling the reaction rate at a lower cost is required.

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

The present application relates to a reactor. According to the exemplary reactor of the present application, the explosion reaction rate of the metal nanoparticle precursor is suppressed by injecting a solution containing the metal precursor into 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, and thus a film having a uniform surface roughness can be produced in a large area.

Hereinafter, a manufacturing method of the present application will be described with reference to the accompanying drawings. The accompanying drawings are merely exemplary and are not intended to limit the method of manufacture of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram exemplarily showing an injection device used in the production method of the present application. Fig.

Exemplary reactors of the present application include a reaction tank and a reaction rate control section.

The reaction tank refers to a water tank or a vessel where the reaction takes place. In one example, the reaction tank may be filled with a solution containing a reactive compound which reacts with the metal precursor.

The metal precursor may include at least one selected from the group consisting of metal nitrate, metal acetate, and metal chloride. The metal is not particularly limited as long as it is a metal capable of reacting with the reactive compound, and may be, for example, 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, It is not. 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 between the metal precursor and the reactive compound may satisfy the following general formula (1).

[Formula 1]

Rp > 1 [mu] m / min

In the general formula (1), Rp represents the rate of increase of the particle size, which is a reactant of the metal precursor and the reactive compound within Ts time,

And Ts represents the time at which the growth of the particle size is saturated.

2 is a graph exemplarily showing the change in particle size or diameter with the 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 time at which the growth of the particle size is saturated corresponds to the time at which the particle size grows explosively according to the reaction time and the boundary of the region where the growth of the particle size slows according to the reaction time, For example, Ts is the time at the point where the first straight line of the graph during the growth time of the particle size and the first straight line of the graph in the time region in which the growth of the particle is saturated in the graph of Fig. 2 . &Lt; / RTI > For example, in the left region of Ts time in Fig. 2, the particle size exponentially grows according to the reaction time, for example, the increase rate of the particle size in the left region of Ts time may be 1 탆 / min or more . 2, the growth of the grain size does not occur or grows at a very low rate depending on the reaction time. For example, the increase rate of the grain size in the right region of the Ts time is 1 탆 / min &Lt; / RTI >

In the case where the reaction of the metal precursor with the reactive compound satisfies the general formula 1, that is, in the case where the increase rate of the particle size, which is a reactant of the metal precursor and the reactive compound, is 1 m / min or more within the Ts time, It is possible to control the particle size of the precursor nanoparticles to be small even at a small cost by effectively suppressing the explosion reaction rate of the metal nanoparticle precursor using the reactor of the application, Area can be manufactured.

In one example, the reactive compound may be a compound represented by the following formula (1).

[Chemical Formula 1]

In 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 can be a Group 1 alkali metal, such as lithium, sodium or potassium, and in one example, sodium.

Each of R ₁ and R ₂ may independently be 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 each independently be 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, and the solution containing the reactive compound may be sodium dimethyldithiocarbamate Mate. &Lt; / RTI >

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) -based solvent such as methanol, 2-methoxyethanol, methanol, And may be, for example, methanol, but is not limited thereto.

The reaction rate control unit controls the reaction rate of the metal precursor and the reactive compound in the reaction tank. As described above, when the metal precursor has a very high reaction rate with the reactive compound such as the compound of Formula 1, an explosive reaction occurs when the first solution and the second solution are simply mixed. In this case, it is difficult to control the particle size of the metal precursor nanoparticles evenly, and a solution containing the metal precursor nanoparticles is coated on the substrate layer It may be difficult to form a uniform and thin coating layer. Thus, in the reactor of the present application, the solution containing the metal precursor is injected into the solution containing the reactive compound by the reaction rate control unit and mixed, whereby the metal precursor nano-particles are highly dispersed and precipitated in the mixed solution, Thus, controlled metal precursor nanoparticles can be formed with a controlled average particle size and a particle size distribution (PSD) with very small standard deviation. Further, in the prior art, an expensive microchannel reactor has been used to control the reaction rate of such a highly reactive compound. However, according to the present reactor, by controlling the reaction rate using the injection device, There is an advantage that the speed can be controlled.

In one embodiment, the solution comprising the metal precursor and the solution comprising the reactive compound may be mixed by a spray device, and in one example, a solution comprising the metal precursor is mixed with the reactive compound To prepare a mixed solution.

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) -based solvent such as 2-methoxyethanol, methanol, And can be, for example, methanol, but is not limited thereto.

The spraying apparatus may be an ultrasonic vibration spraying apparatus, an electro spraying apparatus, or a plasma spraying apparatus. For example, the spraying apparatus may be implemented using a spray header or an electric sprayer equipped with an ultrasonic generator . In this case, the injection may be performed to inject 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, a metal precursor in the solution containing the metal precursor and a reactive compound in the solution containing the reactive compound, for example, a compound of the formula 1, are formed to form a metal precursor nanoparticle of the following formula . Accordingly, the mixed solution may include metal precursor nanoparticles of Formula 2, and may further include a first solvent contained in a solution containing the metal precursor and a solution containing a reactive compound.

(2)

In Formula 2, M ₂ may be a metal of Group 8, Group 11, Group 12 or Group 13, such as aluminum, gallium, indium, thallium, zinc, copper, iron or tin, , Gallium.

Each of R ₃ and R ₄ may independently be 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 ₃ and R ₄ may each independently be 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 2 is selected from the group consisting of Tris (N, N-dimethyldithiocarbamato) -gallium (III), Ga (DmDTC) ₃ ), And the third solution may comprise tris (N, N-dimethyldithiocarbamate) -gallium (III), and preferably the residual sodium dimethyldithio Carbamate and the tris (N, N-dimethyldithiocarbamate) -gallium (III).

In one example, the average particle size 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. In one example, the particle size distribution of the metal precursor nanoparticles is 5 to 40 nm, for example, 10 to 30 nm, and a standard deviation of 10 to 20 nm.

The metal precursor nanoparticles of Formula 2 having the average particle size and particle size distribution as described above can be obtained from the mixed solution. For example, metal precursor nanoparticles of Formula 2 can be obtained by evaporating or centrifuging the first solvent of the mixed solution. The metal precursor nanoparticles obtained can be washed with deionized water, and the washed metal precursor nanoparticles can be dried at a temperature of 50 ° C or more for 4 hours or more.

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

In one example, the metal precursor nanoparticles of Formula 2 obtained above may be dissolved in a second solvent, and the metal precursor nanoparticle solution thus prepared may include the metal precursor nanoparticles of Formula 2. [

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

The coating can be carried out through various coating methods known in the art, for example, spray coating, spin coating, screen printing or dip coating, but is not limited thereto.

As described above, since the prepared metal precursor nanoparticles have a very small average particle size and a narrow range of particle size distribution, and thus the metal precursor nanoparticles have a uniform and small particle diameter, the coating layer of the metal precursor nanoparticle solution 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 Formula 2 can be used without limitation as long as it is a solvent having high evaporability. Examples of the solvent include chloroform (CH ₃ Cl), methanol, Ethanol, and ethers. In one example, it may be chloroform, but it is not limited thereto.

The metal precursor nanoparticle solution layer coated on the base layer may be heat-treated in a nitrogen gas or ammonia gas atmosphere, and the sulfur atom of the compound of formula (2) in the metal precursor nanoparticle solution layer by the heat treatment may be nitrogen gas or ammonia Nitrogen atom of the gas. As a result, a film including a metal nitride layer having a thin thickness and a uniform thickness can be finally produced.

Fig. 3 is a diagram exemplarily showing an apparatus in which heat treatment is performed in the manufacturing method of the present application. Fig.

As shown in FIG. 3, the heat treatment may be performed in a furnace. The heating furnace may be maintained in a nitrogen or ammonia gas atmosphere. The heating furnace may comprise a quartz tube, and a supporting means for fixing the base layer may be disposed in the heating furnace.

In one example, the heat treatment may be performed at a temperature of 500 ° C to 1200 ° C, for example, at a temperature of 600 to 1000 ° C or 800 to 900 ° C, but is not limited thereto. 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 containing the metal precursor nanoparticles of Formula 2 may be formed according to the following Reaction Schemes 1 and 2.

[Reaction Scheme 1]

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

[Reaction 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 production method. Exemplary films of the present application include a very thin and uniform thickness metal nitride layer of several micrometers as produced using the precursor metal precursor nanoparticles obtained by the reactors of the present application, Sulfur atoms in the metal precursor nanoparticles of the metal precursor of the present invention are doped in a part of the metal nitride layer and the sulfur component is detected as a PL spectra on the surface.

Hereinafter, the film of the present application will be described with reference to the accompanying drawings. The accompanying drawings are by way of example and do not limit the film of the present application.

4 is a cross-sectional view schematically showing the 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. Fig.

The metal nitride layer (12) satisfies the following general formula (2) as a spectral luminousness (PL) spectrum measured using a laser having a wavelength of 325 nm.

[Formula 2]

E (I _max ) = E _g - 0.1 x k

In the general formula 2,

E (I _max ) represents the band gap energy at the position having the maximum intensity value of the optical luminescence spectrum,

Eg represents the band gap energy of the metal nitride,

k is a rational number of more than 2 and less than 6.

The term " optical luminescence " refers to a phenomenon in which a material emits light by being stimulated by light, and more specifically, when electrons in a material absorbing light are brought into an excited state and then returned to the original state It means a phenomenon of light emission. The term "photoluminescence (PL) spectrum" refers to a spectrum that irradiates light to a material and exhibits relative intensities representing the distribution of the energy of the light emitted from the material to which the light is irradiated, using optical luminescence , And the intensity of the optical luminescence spectrum has a maximum intensity value (hereinafter referred to as a peak value) in a unique energy band depending on the material. The intensity values of the optical luminescence spectrum are relative values, and thus are expressed in units of a.u (arbitrary unit).

The PL measurement can be performed using a He-Cd laser having a center wavelength of 325 nm as an excitation light source. The measurement temperature is not particularly limited, but it is preferable to perform the measurement at 20 K or less. For example, Omnichrome series 74 He-Cd laser, Acton SpectraPro 2300i spectrometer, Princeton Instruments PI-MAX1024HQ-Blu CCD detector, and the like are examples of devices capable of PL measurement under these conditions. On the other hand, in the PL measurement, there is a case in which the strength of the PL spectrum can not be sufficiently obtained in a crystal having a high carrier concentration in crystals, and evaluation can not be made. In this case, undoped GaN (i-GaN) may be laminated on the crystal surface of the object to be measured by MOCVD or the like to reduce the influence of the carrier during the low-temperature PL measurement, and then measurement can be performed. The thickness of the i-GaN layer to be laminated may be usually 0.01 占 퐉 or more, for example, 0.1 占 퐉 or more, or 0.5 占 퐉 or more. Further, the thickness of the i-GaN layer may be generally 100 mu m or less, for example, 10 mu m or less, or 5 mu m or less. If the thickness of the i-GaN layer to be laminated is too thin, the influence of the carrier can not be sufficiently reduced. If it is too large, the influence of defects occurring in the stacked i-GaN layer can be detected.

The metal nitride layer 12 may be formed by substituting nitrogen atoms in the metal precursor nanoparticles of Formula 2 when the coating layer containing the metal precursor nanoparticles of Formula 2 is heat-treated as described above. In this case, the sulfur atoms in the metal precursor nanoparticles of the above formula (2) are doped into a part of the metal nitride layer (12), and the sulfur component is detected as the optical luminescence (PL) spectrum on the surface. Accordingly, the metal nitride layer 12 satisfies the above-described general formula (2) by using a PL spectra measured using a laser having a wavelength of 325 nm.

In one example, when the metal nitride layer is a gallium nitride layer, the metal nitride layer satisfying the formula 2 has a maximum intensity value of the optical luminescence (PL) measured using a laser having a wavelength of 325 nm of 2.8 to Lt; RTI ID = 0.0 > eV. &Lt; / RTI > This is because as described above, the sulfur atoms in the metal precursor nanoparticles of Chemical Formula 2 are doped into the metal nitride layer 12, and the sulfur component is detected as the PL spectra on the surface.

For example, in the case of the gallium nitride layer, as shown in Fig. 7, the band gap energy at the position having the maximum intensity value of the luminousness spectrum represented by the sulfur component is 2.95 eV, and the band gap energy of gallium nitride is 3.44 eV , The 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 can be confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The metal nitride layer 12 is formed by removing the surface oxide layer with an ion gun using an inert gas, The maximum intensity value of the XPS spectrum measured on the Kα X-ray basis 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 in the vicinity of about 164 eV (carbon 1 s peak 284.5 eV reference, sulfur 2 p3 / 2 peak). It is also confirmed by quantitative analysis through XPS that sulfur is contained in an amount of 5 wt% or less.

The "XPS analysis" is a method of using X-rays as a light source in the electro-spectroscopy. When X-rays are irradiated onto a substance, the photoelectrons are emitted to the outside of the substance. And therefore, it means a method of examining the atomic composition of the substance and the bonding state of the electrons.

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

In the above, the centerline average roughness is obtained by extracting the center line average roughness by a reference length L in the direction of the average line in the roughness curve, calculating the roughness curve as a function y = f (x ) Denotes a value which can be obtained by the following formula (1) in terms of micrometers (占 퐉). The center line average roughness is measured under the standards of JIS B0031, JIS B0601 or ISO 468.

[Equation 1]

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

The base layer 11 may have a melting point of 550 DEG C or more. If the melting point of the substrate layer 11 is less than 550 ° C, there may occur a problem that the components of the base layer are dissolved in the heat treatment process and carbon or carbon component related by-products remain in the metal nitride layer. The base material layer 11 may include at least one material selected from the group consisting of alumina, silicon carbide (SiC), silicon, quartz, glass and stainless steel. In one example, But 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 탆 or less, for example, 8 탆 or less, or 5 탆 or less, but is not limited thereto.

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

According to the reactor of the present application, the explosion reaction rate of the metal nanoparticle precursor is suppressed by injecting a solution containing the metal precursor into a solution containing a reactive compound having a very high reactivity with the metal precursor, The particle size of the particles can be controlled to be small, and thus a film having a uniform surface roughness can be produced in a large area.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an exemplary reactor of the present application. FIG.
FIG. 2 is a graph showing changes in particle size with respect to reaction time. FIG.
Fig. 3 is an exemplary view showing an apparatus in which the heat treatment is performed in the method of the present application. Fig.
4 is a cross-sectional view schematically showing the film of the present application.
5 (a) is a ¹ H-NMR spectrum of Ga (DmDTC) ₃ nanoparticles, and FIG. 5 (b) is a graph and a photograph showing the size distribution and shape of Ga (DmDTC) ₃ nanoparticles.
6 (a) is an XRD pattern of a gallium nitride layer due to thermal decomposition deformation of a Ga (DmDTC) ₃ film in an environment where ammonia flows, and FIG. 6 (b) is a SEM photograph of a surface and a cross section of a gallium nitride layer .
Figure 7 shows high resolution XP spectra of Ga 2p _3/2 , N 1s and O 1s peaks.
8 shows the PL spectrum of the gallium nitride layer at room temperature.
FIG. 9 shows an XRD pattern and an SEM photograph of an epitaxial gallium nitride film grown on a gallium nitride layer pyrolyzed by MOCVD.
10 is an image of a gallium nitride thin film prepared in Comparative Example using a scanning electron microscope (SEM).

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the scope of the present application is not limited by the following description.

The physical properties in the following Examples and Comparative Examples were measured by the following methods and apparatuses.

The synthesized metal precursor Identification of nanoparticles

The metal precursors synthesized in the following Examples and Comparative Examples The nanoparticles were confirmed by ¹ H-Fourier transform magnetic resonance system ( ¹ H-FT-NMR, Bruker DPX300).

The synthesized metal precursor Measure the size of nanoparticles

The metal precursors synthesized in the following Examples and Comparative Examples The size of the nanoparticles was measured using a particle size analyzer (Beckman Coulter, Inc.) as well as a transmission electron microscope (TEM, Hitachi, H-7600) and X-ray diffraction (XRD, PANalytical, X'pert PRO) N5).

Measurement of structure and morphological properties of metal nitride layers

Structural and morphological properties of the metal nitride layer formed in the following examples and comparative examples were measured using a scanning electron microscope (SEM, Hitachi, S-4100).

Measurement of optoelectronic properties of metal nitride layers

The photoelectric 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 the compositional ratio and bonding of the 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).

Measurement of center line average roughness of metal nitride layer

The centerline average roughness of the metal nitride layer formed in the following examples and comparative examples was calculated by using the formula (1) based on the height data obtained at this time by using AFM (atomic force microscope).

Example 1

A gallium nitride layer was formed on the alumina base layer in the following manner.

(N, N-dimethyldithiocarbamate) -gallium (III) (Ga (S ₂ CN (CH ₃ ) ₂ ) ₃ and Ga (DmDTC) ₃ ) as a precursor of the gallium nitride layer, The nanoparticles were synthesized by ultrasonic injection.

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

The gallium nitrate solution was ultrasonically jetted onto the sodium dimethyldithiocarbamate ligand solution at room temperature for 30 minutes and the flow rate of the gallium nitrate solution during the injection process was maintained at 10 ml / hr. The Ga (DmDTC) ₃ nanoparticles were synthesized by a very slow precipitation 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. Average particle diameter of the produced 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 ultrasonically in chloroform (CHCl ₃ ) solvent at room temperature for 1 hour.

The solution in which the Ga (DmDTC) ₃ nanoparticles were dispersed 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, Thereby forming a film having a thickness of Ga (DmDTC) ₃ 5 탆. Thereafter, using the apparatus shown in Fig. 2, Ga (DmDTC) ₃ The film was heat-treated at 850 ° C for 10 minutes under an ammonia (NH ₃ ) atmosphere at a flow rate of 170 sccm. After the pyrolysis process, the sample was cooled to room temperature under a nitrogen atmosphere to obtain a gallium nitride To form a layered film. In this case, the center line surface roughness of the gallium nitride layer was measured at 7 nm.

Thereafter, a gallium nitride film was epitaxially grown on the produced gallium nitride layer by MOCVD. At this time, the deposition time was maintained at 5 minutes to test the initial growth of the gallium nitride film, and 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 탆 was formed on the alumina base layer was prepared 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 占 퐉 was formed on the alumina base layer was prepared 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. The surface roughness of the center line 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 탆 was formed on the alumina base layer was prepared 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. The center line 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 mixed with the sodium dimethyldithiocarbamate ligand solution by ultrasonic irradiation but simply mixed, and the formed nanoparticles were used To prepare a gallium nitride thin film. 10 is an image of a gallium nitride thin film prepared in Comparative Example using a scanning electron microscope (SEM). As shown in FIG. 10, the gallium nitride thin film produced was unable to form a continuous thin film, and it was very difficult to form the thin film with a thickness of 5 μm, and showed a very uneven and irregular porous structure. Accordingly, the surface roughness of the gallium nitride thin film could not be calculated according to the above equation (1).

The average particle diameter of the Ga (DmDTC) ₃ nanoparticles prepared above was about 0.1 to 0.5 μm, and the standard deviation of particle diameter of the formed nanoparticles was about 0.1 μm.

5 (a) shows the ¹ H-NMR spectrum of Ga (DmDTC) ₃ nanoparticles. The spectra represent four peaks of 0 ppm, 1.55 ppm, 3.40 ppm and 7.26 ppm assigned to tetramethylsilane (TMS), water in CDCl ₃ , Ga (DmDTC) ₃ and CHCl ₃ in CDCl ₃ , respectively . The tetramethylsilane was used as an internal reference for chemical shift calibration and the peak of the single line at 3.40 ppm is closely related to the chemical shift of the Ga (DmDTC) ₃ material. 5 (b) is a graph and a photograph showing the size distribution and shape of Ga (DmDTC) ₃ nanoparticles. 5 (b), the Ga (DmDTC) ₃ nanoparticles synthesized by the ultrasonic jetting method are well mono-dispersed so as to have an average particle size of 28.5 nm and a standard deviation of 13.3 nm Respectively. In general, the precipitation reaction of gallium nitrate (Ga (NO ₃ ) · 8H ₂ O) and sodium dimethyldithiocarbamate ((CH ₃ ) ₂ NCSSNA · 2H ₂ O) takes place very quickly, This is relatively difficult. On the other hand, the ultrasonic jetting method is a useful method for controlling the reaction rate, because the size of a plurality of gallium precursor particles in the droplet jetted by ultrasonic waves is relatively small. Therefore, the abrupt reaction of forming large particles was effectively prevented, and the Ga (DmDTC) ₃ nanoparticles were easily dispersed in the chloroform solvent.

6 (a) shows an XRD pattern of a GaN layer by thermal decomposition of a Ga (DmDTC) ₃ film in an environment where ammonia flows. The XRD peak of the gallium nitride layer is observed mainly at 34.6 degrees and 73.1 degrees 2 theta and is assigned and contributed from the (0002) and (0004) planes of the hexagonal structure phase. In addition, a peak due to the? -Ga2S3 phase was not observed in the XRD pattern. Ga (DmDTC) turns γ-Ga ₂ S _3-phase under the _third phase is more than 500 ℃ nitrogen environment and the Ga (DmDTC) ₃ the addition of γ-Ga ₂ S _3, and CN (CH ₃₎ which is thermally decomposed in water . Therefore, pyrolysis reaction from Ga (DmDTC) ₃ to gallium nitride layer under ammonia can be simply expressed by thermal decomposition of Ga (DmDTC) ₃ and chemical reaction between γ-Ga ₂ S ₃ and ammonia. This reaction can be summarized as schemes 1 and 2.

[Reaction Scheme 1]

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

[Reaction Scheme 2]

Ga ₂ S ₃ + 2NH ₃ ? 2GAN + 3H ₂ S

The reason that the pyrolyzed gallium nitride layer is well arranged in the (0002) preferential culture direction was expected from the recrystallization process during the pyrolysis reaction. As shown in the above reaction 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 nitrogen (N) component. At this time, the pyrolyzed gallium nitride layer undergoes a recrystallization process and, due to the low surface energy of the (0002) plane in the hexagonal structure, the crystalline structure of gallium nitride is mainly arranged in the (0002) preferential growth direction. Furthermore, the presence of the amorphous phase in the gallium nitride layer can be confirmed from the gentle slope observed in the XRD pattern. 6 (b) shows an SEM photograph of the surface and cross-section of the gallium nitride layer, showing a dense structure and a small crystalline phase. The gallium nitride layer did not show any voids or cracks despite the thickness of 5 탆. 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. The grain boundaries usually have an amorphous phase, and the crystal structure of the gallium nitride layer is terminated at the grain boundary. In addition, nitrogen and sulfur have different oxidation numbers, which means that the sulfur bonds in gallium nitride have modified the crystalline structure of gallium nitride. They can lead to crystalline disorder and defects in the film.

7 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 area (1120.8 eV) due to oxygen mixing was very small compared to the peak area (1118.3 eV) due to nitrogen mixing, indicating that the oxygen contamination is sufficiently low in the non-vacuum process. The deconvoluted peaks of N 1s were located at 396.6 eV and 397.7 eV, respectively, due to Ga-N and Ga-S bonds. The elemental consumption of N for the 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 evidenced in Scheme 2 above and the remaining sulfur atoms are used to form GaN (GaN: S) in which sulfur is doped in an ammonia environment . The peaks of O 1s were observed at 530.8 and 531.8 eV, respectively. Generally, the oxygen peak is in the range of 529 to 535 eV, the peak in the vicinity of 529 to 530 eV is the lattice oxygen, but the peak in the range of 530 to 535 eV is related to the absorption of carbon at the film surface or contamination by organic materials do. In this case, O1s XPS peaks at 530.8 eV and 531.8 eV are assigned to the chemical adsorption of the film surface.

8 shows the PL spectrum of the 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, indicating the formation of a shallow donor level due to sulfur (S) on the nitrogen (N) site of the gallium nitride layer . &Lt; / RTI > As described above in the XPS results, a small amount of sulfur (S) remains in the gallium nitride in the pyrolysis process, and the shallow donor level can be formed due to the substitution of sulfur (S) in the nitrogen (N) have. Generally, group 4 on gallium (Ga) sites and group 6 on nitrogen (N) sites are considered as shallow donors in gallium nitride. Thus, the appearance of these peaks results from the transition from a shallow donor to a shallow acceptor. Green luminescence (GL) at 2.69 eV originates from different charge states of defects due to oxygen substitution at gallium vacancies and nitrogen sites. As a result, the appearance of weak band edge emission and BL-GL band is explained by various defects due to abundant gallium, nitrogen deficiency and sulfur substitution in the gallium nitride layer, as well as various pathways of many disordered and non-radiative remnants. .

FIG. 9 shows an XRD pattern and an SEM photograph of an epitaxial gallium nitride film grown on a gallium nitride layer pyrolyzed by MOCVD. The epitaxial growth of gallium nitride proceeds in accordance with the following Reaction Schemes 3 and 4.

[Reaction Scheme 3]

_{Ga (CH 3) 3 (g} ) + HCl (g) → GaCl (g) + CH x group (g)

[Reaction 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 preferential orientation in the (0002) direction due to the hexagonal Wurtzite structure. In addition, the grown gallium nitride film showed lateral growth on the substrate, but the gallium nitride film on the bare sapphire substrate grew upward in the z-axis direction. From this it can be seen that the adsorbed atoms are strongly mixed due to the single-epitaxial properties between the pyrolyzed gallium nitride layer and the grown gallium nitride.

10: Film
11: substrate layer
12: metal nitride layer

Claims

A reaction tank filled with a solution containing a reactive compound which reacts with a metal precursor; And a reaction rate controller for controlling a reaction rate of the metal precursor and the reactive compound in the reaction vessel,
Wherein the reaction rate control unit is a spraying device in which a solution containing a metal precursor is sprayed at a flow rate of 20 ml / hr or less,
Wherein the reaction between the metal precursor and the reactive compound satisfies the following general formula 1:
[Formula 1]
Rp? 1 占 퐉 / min
In the general formula (1), Rp represents the rate of increase of the particle size, which is a reactant of the metal precursor and the reactive compound within Ts time,
And Ts represents the time at which the growth of the particle size is saturated.

delete

The reactor according to claim 1, wherein the injection device is an ultrasonic vibration injection device, an electric injection device, or a plasma injection device.

2. The reactor according to claim 1, wherein the injector comprises a nozzle through which a solution containing a metal precursor is injected, and an injection controller for controlling an injection speed of the solution.

The reactor according to 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 according to 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 process according to claim 1, wherein the reactive compound is a compound represented by the following formula (1):
[Chemical Formula 1]

In Formula 1,
M ₁ is a Group 1 metal,
R ₁ and R ₂ each independently represent alkyl having 1 to 12 carbon atoms.