KR20230168373A - Integrated chemical vapor deposition microscope apparatus and control method for low-dimensional material synthesis using thereof - Google Patents

Abstract

An integrated chemical vapor deposition microscope device and a method for controlling the synthesis of low-dimensional materials using the same are disclosed. An integrated chemical vapor deposition microscopy device according to the present invention includes a heating furnace for vaporizing a first precursor; A gas flow unit provided in communication with the heating furnace and controlling the amount of inert gas supplied to the heating furnace; A reaction stage equipped with a reaction chamber supplied with a vaporized first precursor carried by an inert gas and a substrate coated with a second precursor that reacts with the first precursor, and an observation window provided in the reaction chamber, the temperature of which is adjustable. ; and a microscope unit disposed opposite the observation window to observe and photograph the nucleation and growth of the compound synthesized by the first precursor and the second precursor in the reaction chamber in real time.

Description

Integrated chemical vapor deposition microscope apparatus and control method for low-dimensional material synthesis using the same}

The present invention relates to an integrated chemical vapor deposition microscopy device and a method for controlling the synthesis of low-dimensional materials using the same.

Two-dimensional materials with various electrical properties can be implemented into devices through vertical and horizontal assembly. Even if two-dimensional materials are stacked in dozens of layers, the thickness is only a few tens of nanometers, making it possible to make the device very small.

For example, bandgap control achieved through various combinations of transition metals and chalcogens can be used in a variety of electronic devices, solar materials, energy materials, and catalyst materials, so its field of application is very wide.

Two-dimensional materials, also called van der Waals materials, are materials that have a thickness of several atomic layers and spread widely on a plane, and have a wide variety of types and characteristics.

Two-dimensional materials include graphene, hexagonal boron nitride, oxide, and transition metal chalcogenide (e.g., MoS ₂ , WS ₂ , MoSe ₂ , WSe ₂ , ReS ₂ , Any of ReSe ₂ , MoTe ₂ , WTe ₂ , ZrS ₂ , ZrSe ₂ , NbS ₂ , NbSe ₂ , GaSe, GaTe, InSe, Bi2Se ₃ ), black phosphorus, silicene and borophene It may include one or a combination thereof.

In particular, transition metal chalcozene compounds have semiconductor properties, can adjust the band gap from 1.0 to 2.5 eV depending on the combination of transition metal and chalcogen elements, and can exhibit various optoelectric properties, leading to active research as next-generation materials. It is in progress and can be grown in a large area, making it suitable for photoelectric applications. However, defects that occur during the growth of transition metal chalcogen compounds (for example, chalcogen defects in the lattice) and control of the number of layers still remain problems to be solved, and efficient growth methods are needed.

In the case of transition metal chalcogen compounds, many growth studies are being conducted through chemical vapor deposition (CVD), but in order to establish growth conditions, the growth conditions are changed and the characteristics are observed through samples after growth is completed. In other words, in most cases, it was a 'post-growth analysis method', so a lot of time and effort was needed to establish growth conditions.

Accordingly, a method that can observe the effects of growth factor regulation in real time throughout the entire growth process is urgently needed, and in order to analyze the growth mechanism, the following methods as well as existing studies on changes in the shape and characteristics of grains according to growth conditions are needed. was introduced. In the case of graphene, the growth trajectory and time-dependent growth process of multilayer graphene could be known by varying the time when carbon isotopes were supplied from the chemical vapor deposition device, and structural changes in the two-dimensional material were studied using transmission electron microscopy and scanning electron microscopy. It has been done. However, most of these methods can only view the change process of a single precursor on a substrate and are not applicable to active growth that requires two or more precursors.

Therefore, there is a need for technology that can observe and control synthesized two-dimensional materials such as transition metal chalcogen compounds in real time.

Republic of Korea Patent No. 10-2198340 (announced on January 4, 2021)

Therefore, the technical problem that the present invention aims to solve is to observe and film the nucleation and growth process of the compound being synthesized in real time, and to accurately analyze the effect of growth conditions by analyzing the growth process of the compound in real time from the captured image information. The aim is to provide an integrated chemical vapor deposition microscopy device and a method for controlling the synthesis of low-dimensional materials using the same.

According to one aspect of the present invention, a heating furnace for vaporizing the first precursor; a gas flow unit provided in communication with the heating furnace and controlling the amount of inert gas supplied to the heating furnace; a reaction chamber containing a substrate supplied with the vaporized first precursor carried by the inert gas and coated with a second precursor reacting with the first precursor; and an observation window provided in the reaction chamber, wherein temperature is controlled. This possible reaction stage; and an integrated chemical vapor deposition microscope including a microscope unit disposed opposite the observation window to observe and photograph the nucleation and growth of the compound synthesized by the first precursor and the second precursor in the reaction chamber in real time. A device may be provided.

The microscope unit includes a support portion supporting the reaction stage; An objective lens disposed opposite the observation window; And it may include an imaging module disposed in-line with the objective lens to observe and photograph nucleation and growth of the compound in real time.

The imaging module may include a CCD camera (Charge Coupled Device camera).

The CCD camera may be equipped with a band-pass filter to monochromatize light.

The microscope unit includes a light source; A beam splitter provided between the objective lens and the imaging module; a collimator lens provided between the beam splitter and the light source; An imaging lens provided between the beam splitter and the imaging module; It may further include a spectroscope provided between the imaging lens and the imaging module.

It may further include a display module connected to the imaging module to display nucleation and growth of the compound.

Connected to the heating furnace, the gas flow unit, the reaction stage, and the microscope unit, the captured nucleation and growth images of the compound are stored, the growth process of the compound is analyzed, and the temperature of the first precursor and the It may further include a control unit that controls the growth conditions of the compound by adjusting the temperature of the second precursor and the amount of the inert gas.

It may further include a vibration-free optical table on which the gas flow unit, the reaction stage, and the microscope unit are fixed.

The first precursor is a chalcogen precursor, and the chalcogen precursor is at least one element selected from the group consisting of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te), or a compound containing these elements It includes, wherein the second precursor is a transition metal precursor, and the transition metal precursor is molybdenum (Mo), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), and iron. It may include at least one selected from the group consisting of (Fe), cobalt (Co), nickel (Ni), niobium (Nb), and tungsten (W).

According to another aspect of the invention, (a) vaporizing the first precursor; (b) supplying the vaporized first precursor to a reaction chamber of a reaction stage containing a substrate coated with the second precursor to synthesize a compound; (c) observing and photographing the nucleation and growth of the compound in the reaction chamber in real time; and (d) controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscopy device, including the step of controlling the growth conditions of the compound by analyzing the growth process of the compound from the captured nucleation and growth image of the compound. A method may be provided.

The step (d) includes adjusting the temperature of the first precursor; adjusting the temperature of the second precursor; And it may include adjusting the amount of the inert gas.

In step (c), the nucleation and growth of the compound can be observed and photographed in real time through an observation window provided in the reaction chamber using a microscope unit.

The microscope unit includes a support portion supporting the reaction stage; An objective lens disposed opposite the observation window; And it may include an imaging module disposed in-line with the objective lens to observe and photograph nucleation and growth of the compound.

(e) may further include displaying and storing the nucleation and growth of the compound photographed in step (c).

An embodiment of the present invention observes and photographs in real time the nucleation and growth process of a compound synthesized by a first precursor and a second precursor in a reaction chamber, and analyzes the growth process of the compound in real time from the captured image information. You can.

In addition, embodiments of the present invention can analyze the growth process of a compound in real time and change the growth conditions, such as the temperature of the precursors and the amount of inert gas, to accurately analyze the effect of the growth conditions in real time.

1 is a diagram showing an integrated chemical vapor deposition microscope device according to the present invention.
Figure 2 is a schematic diagram of an integrated chemical vapor deposition microscope device according to the present invention.
Figure 3 is a diagram showing a reaction stage according to the present invention.
Figure 4 is a diagram schematically showing a reaction chamber according to the present invention.
Figure 5 is a schematic diagram schematically showing a microscope unit according to the present invention.
Figure 6 is a diagram showing the process by which the nucleus of MoO ₃ changes at each temperature after the start of the reaction in the integrated chemical vapor deposition microscope device according to the present invention.
Figure 7 is a diagram showing the relationship between the density of nuclei and the size of grains resulting from the difference according to the method of processing MoO ₃ on the substrate.
Figure 8 is a diagram showing a MoO ₃ precursor with uniform distribution obtained through sublimation.
Figure 9 is a diagram showing the number of nuclei versus the area of grains.
Figure 10 is a diagram showing contrast images of various MoS ₂ crystals by layer number when determining the number of layers of MoS ₂ crystals using optical contrast measurement.
Figure 11 is a diagram showing the correlation between the number of layers and optical contrast when determining the number of layers of a MoS ₂ crystal using an optical contrast measurement method.
Figure 12 is a diagram showing the control of the temperature of each precursor ( T _MoO3 , T _S ) and the flow rate of inert gas ( F _Ar ) during the growth process of MoS ₂ according to growth time.
Figure 13 is a diagram showing the contour line of MoS ₂ outline according to growth time during the growth process of MoS ₂ according to growth time.
Figure 14 is a diagram showing images of MoS ₂ crystal growth over time during the growth process of MoS ₂ according to growth time.
Figure 15 is a diagram showing a graph fitted with data obtained by measuring the length of a vertex or side from the center of a triangular crystal grain of MoS ₂ crystal growth over time during the growth process of MoS ₂ according to growth time.
Figure 16 is a diagram showing grains growing through oscillation through the difference between the fitting graph and the actual graph during the growth process of MoS ₂ according to growth time.
Figure 17 is a diagram showing the change in shape according to the equivalence of Mo and S in the MoS ₂ plane.
Figure 18 is a diagram showing the MoS ₂ crystal shape according to the partial pressure of each precursor through kinetic Monte Carlo simulation.
Figure 19 is a diagram showing the relationship between the experimental partial pressure and the shape of MoS ₂ formed.

In order to fully understand the present invention, its operational advantages, and the objectives achieved by practicing the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the attached drawings. The same reference numerals in each drawing indicate the same member.

Figure 1 is a diagram showing an integrated chemical vapor deposition microscope device according to the present invention, Figure 2 is a schematic diagram of an integrated chemical vapor deposition microscope device according to the present invention, Figure 3 is a diagram showing a reaction stage according to the present invention, Figure 4 is a diagram schematically showing a reaction chamber according to the present invention, and Figure 5 is a schematic diagram schematically showing a microscope unit according to the present invention.

Referring to Figures 1 to 5, the integrated chemical vapor deposition microscope device 100 according to the present invention is provided in communication with the heating furnace 110 and the heating furnace 110 for vaporizing the first precursor, and the heating furnace 110 ), a gas flow unit 120 that controls the amount of inert gas supplied to the reaction stage ( 130), a microscope unit 140 that observes and photographs in real time the nuclear formation and growth of the compound synthesized in the reaction chamber 131 through the observation window 132, and the images taken by the microscope unit 140 It includes a display module 150 that displays the nucleation and growth of the compound, and a control unit 160 that controls the growth conditions of the compound.

In this embodiment, the first precursor is a chalcogen precursor, and the chalcogen precursor includes at least one element selected from the group consisting of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te) or these. It may be a compound that does. Additionally, in this embodiment, the second precursor is a transition metal precursor, and the transition metal precursor is molybdenum (Mo), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), and iron ( It may include at least one selected from the group consisting of Fe), cobalt (Co), nickel (Ni), niobium (Nb), and tungsten (W). Preferably, it may include Mo, W, or both. Hereinafter, a first precursor and a second precursor, which are two-dimensional materials, will be described as an example. However, the rights of the present invention are not limited to two-dimensional materials and can be extended to one-dimensional materials (e.g., carbon nanotubes, nanocrystals, etc.).

Additionally, in this embodiment, the inert gas may include at least one selected from the group consisting of argon gas, nitrogen gas, and helium gas.

In this embodiment, the heating furnace 110 heats and vaporizes the chalcogen precursor, which is the first precursor. In this embodiment, the chalcozene precursor is vaporized into a gas phase in the heating furnace 110, and then the vaporized chalcozene precursor is moved into the reaction chamber 131 while flowing an inert gas.

The heating furnace 110 is connected in communication with an inert gas storage tank 125 in which argon gas, an inert gas, is stored, and within the heating furnace 110, the chalcogen precursor is vaporized at 200 ° C. to 300 ° C. or 250 ° C. to 300 ° C. It can be.

And the amount of vaporized chalcogen precursor flowing from the heating furnace 110 into the reaction chamber 131 of the reaction stage 130 is controlled by the gas flow unit 120.

In this embodiment, the gas flow unit 120 is provided between the heating furnace 110 and the inert gas storage tank 125 and controls the amount of inert gas supplied from the inert gas storage tank 125 to the heating furnace 110. do.

The inert gas moves the vaporized chalcozene precursor in the heating furnace 110. By controlling the amount of inert gas supplied to the heating furnace 110, the amount of vaporized chalcozene precursor supplied to the reaction chamber 131 is adjusted. It can be adjusted.

The reaction stage 130 according to this embodiment synthesizes a transition metal chalcozene compound by reacting a chalcogen precursor, which is a first precursor, with a transition metal precursor, which is a second precursor. In order to synthesize a transition metal chalcogen compound, the reaction stage 130 can control temperature.

As shown in FIGS. 3 and 4, the reaction stage 130 includes a reaction chamber 131 containing a substrate 135 coated with a transition metal precursor, and an observation window 132 provided in the reaction chamber 131. Includes. In addition, the reaction stage 130 is provided to communicate with the reaction chamber 131, and is connected to the supply port 133 through which the chalcogen precursor transported by the inert gas in the heating furnace 110 is supplied, and the reaction chamber 131. It is provided and further includes an outlet 134 through which inert gas supplied to the reaction chamber 131 is discharged.

In this embodiment, the temperature within the reaction chamber 131 can be adjusted to enable reaction up to 1000°C. And a substrate 135 coated with a transition metal precursor is embedded within the reaction chamber 131.

For example, the nuclear density of the transition metal chalcogen compound can be adjusted depending on the method of treating MoO ₃ on the silicon (SiO ₂ /Si) substrate 135. For example, when MoO ₃ was prepared by dropcasting or spincoating a solution in which sodium cholate was added to MoO ₃ and dispersed in water onto the silicon substrate 135, the nuclear density of the transition metal chalcogen compound was very low, and on the other hand, the powder type In the case of MoO ₃ obtained by sublimating MoO ₃ at high temperature, the nuclear density of the transition metal chalcogen compound is very dense.

The observation window 132 is provided at the upper part of the reaction chamber 131 to enable observation of the nucleation and growth process of the transition metal chalcogen compound synthesized within the reaction chamber 131 using a microscope unit 140, which will be described later.

The observation window 132 has a wide observation area and is provided so that a thin coverslip can be mounted. In this embodiment, the coverslip is made of a quartz plate with a thickness of 0.15 mm or less, so that a clear image can be obtained.

An observation window 132 is provided at the top of the reaction chamber 131 to observe the transition metal chalcogen compound synthesized in the reaction chamber 131, and a microscope unit 140 is placed opposite the observation window 132. This is prepared.

The microscope unit 140 according to this embodiment observes and photographs the nucleation and growth process of the transition metal chalcogen compound in the reaction chamber 131 in real time.

The microscope unit 140 has a support portion 141 supporting the reaction stage 130, an objective lens 142 disposed opposite to the upper part of the observation window 132, and is disposed inline with the objective lens 142 to perform transition. It includes an imaging module 143 that observes and photographs the nucleation and growth of the metal chalcogen compound in real time.

The support portion 141 is on which the reaction stage 130 is seated and supports the lower surface of the reaction stage 130. And an objective lens 142 is provided to face the support part 141 and the reaction stage 130.

The objective lens 142 is disposed opposite to the upper part of the observation window 132 of the reaction chamber 131, and allows the synthesis of the transition metal chalcogen compound within the reaction chamber 131 to be observed. In this embodiment, the objective lens 142 may be composed of a 100x long walking objective lens 142 capable of high-resolution imaging, and the reaction chamber 131 may be removed through a thin coverslip to minimize chromatic aberration and obtain high-quality images. A transition metal precursor (eg, MoO ₃ ) is used to focus the coated substrate 135 (see FIGS. 1, 2, and 3).

The imaging module 143 is placed in-line with the objective lens 142 and can observe and photograph the nucleation and growth process of the transition metal chalcogen compound in the reaction chamber 131 in real time.

The imaging module may include a CCD camera (Charge Coupled Device camera, 143). In this embodiment, the existing CMOS camera can be converted into a CCD camera 143 to increase the quantification of the image and the number of frames per second can be improved to 20 fps.

The display module 150 according to this embodiment displays and stores images or images of the nucleation and growth process of the transition metal precursor compound captured by the CCD camera 143. The display module 150 displays real-time video or images through a monitor connected to the CCD camera 143. Accordingly, changes in the size and shape of crystal grains during the nucleation and growth process of the transition metal precursor compound can be observed in real time through the video or image displayed on the display module 150 according to trends of time and temperature.

On the other hand, the present invention enables macroscopic analysis of growth of micrometers or more, allowing changes in the size and shape of grains during the growth process to be recorded in image form according to trends of time and temperature, and using additional spectroscopic information to compare existing approaches. presents an efficient approach to control physical properties such as defects and number of layers that are difficult to solve. In other words, the present invention presents a chemical vapor deposition-spectroscopy integrated platform technology that can observe and control two-dimensional materials synthesized in real time through a feedback process of growth conditions using spectroscopic observation.

In this embodiment, in order to determine the number of layers of the transition metal chalcogen compound in the reaction chamber 131, a 620 nm band-pass filter (not shown) for monochromating light can be mounted on the CCD camera 143. The band pass filter is used to monochromatize light and measure contrast according to the number of layers in real-time observation of the growth process of the transition metal chalcogen compound on the 285 nm SiO ₂ /Si substrate 135.

Additionally, in this embodiment, Raman spectroscopy can be applied to determine defects in the transition metal chalcogen compound within the reaction chamber 131. As shown in FIG. 5, the microscope unit 140 according to this embodiment includes a laser light source 145, a beam splitter 147 provided between the objective lens 142 and the imaging module 143, and a beam splitter. A band pass filter (not shown) provided between the laser light source, a collimator lens 146 provided between the beam splitter 147 and the laser light source 145, and an image forming device provided between the beam splitter 147 and the imaging module 143. It may further include a lens 148, a spectroscope (not shown) provided between the imaging lens 148 and the imaging module 143, and a long pass filter 149 provided between the imaging lens 148 and the spectrometer. At this time, the CCD camera 143, which is an imaging module, detects the Raman spectrum image, and the display module 150 displays the Raman spectrum image. Defects in transition metal chalcogen compounds can be determined through Raman spectra.

Conventionally, in the case of transition metal chalcogen compounds, many growth studies have been conducted using chemical vapor deposition, but in order to establish growth conditions, the growth conditions are changed and the characteristics are observed through samples after growth is completed, that is, 'post-growth analysis method'. In most cases, it took a lot of time and effort to establish growth conditions.

Accordingly, a method to observe the effects of growth factor control in real time throughout the entire growth process was urgently needed, and in order to analyze the growth mechanism, the following methods were used in addition to existing studies on changes in the shape and characteristics of grains according to growth conditions. was introduced. In other words, for example, in the case of graphene, the growth trajectory and time-dependent growth process of multilayer graphene could be known by varying the time when carbon isotopes were supplied from the chemical vapor deposition device, and the two-dimensional material using transmission electron microscopy and scanning electron microscopy Structural changes were studied. However, most of these methods can only view the change process of one precursor on the substrate 135 and cannot be applied in the case of active growth that requires two or more precursors. To overcome these limitations, a chemical vapor deposition-spectroscopy integrated platform technology is needed that can observe and control two-dimensional materials synthesized in real time through a feedback process of growth conditions using spectroscopic observation. The integrated chemical vapor deposition microscope device 100 according to the present invention can observe changes that occur in real time when several variables are systematically changed in a single growth process using an integrated chemical vapor deposition-spectroscopy platform. The present invention enables macroscopic analysis of growth of micrometers or more, allowing changes in the size and shape of grains during the growth process to be recorded in the form of images according to trends of time and temperature, and uses additional spectroscopic information to solve problems in existing approaches. We present an efficient approach to control physical properties such as defects and number of layers, which are difficult to achieve.

That is, the integrated chemical vapor deposition microscope (ICVDM) device according to the present invention can present the entire growth process (nucleation-growth-termination) of a two-dimensional material in a spectroscopic manner using imaging spectroscopy. At the same time, it is an equipment that can implement the feedback of growth conditions in real time. Feedback of growth conditions can enable real-time control of defects and number of layers during the growth process of two-dimensional materials and is of great help in developing growth methods for various low-dimensional materials.

Meanwhile, the control unit 160 according to this embodiment allows real-time observation and control of two-dimensional materials synthesized through a feedback process.

The control unit 160 is connected to the heating furnace 110, the gas flow unit 120, the reaction stage 130, and the microscope unit 140. And the control unit 160 stores the captured images of nucleation and growth of the transition metal chalcogen compound and analyzes the growth process of the transition metal chalcogen compound. In addition, the control unit 160 can control the growth conditions of the transition metal chalcogen compound by adjusting the temperature of the chalcogen precursor, which is the first precursor, the temperature of the transition metal precursor, which is the second precursor, and the amount of inert gas.

And the gas flow unit 120, reaction stage 130, microscope unit 140, and control unit 160 are fixed to the vibration-free optical table 170 to attenuate vibration. Through this, a clear image can be obtained while acquiring images of the nucleation and growth of the transition metal chalcogen compound in the reaction chamber 131.

A method for controlling the synthesis of low-dimensional materials using the integrated chemical vapor deposition microscope device 100 according to the present invention configured as described above will be described as follows.

The method for controlling the synthesis of low-dimensional materials using the integrated chemical vapor deposition microscope device 100 according to the present invention includes the steps of vaporizing a first precursor, and placing the vaporized first precursor on a substrate 135 coated with a second precursor. A step of synthesizing a compound by supplying it to the reaction chamber 131 of the reaction stage 130, observing and filming the nucleation and growth of the compound in the reaction chamber 131 in real time, and nucleation of the filmed compound. And a step of displaying and storing the growth, and analyzing the growth process of the compound from the captured nucleation and growth images of the compound, and controlling the growth conditions of the compound.

As described above, the first precursor is a chalcogen precursor and the second precursor is a transition metal precursor.

In the step of evaporating the first precursor, the chalcogen precursor may be vaporized at 200 ° C to 300 ° C or 250 ° C to 300 ° C in the heating furnace 110 connected to the inert gas storage tank 125. The chalcogen precursor vaporized in the heating furnace 110 is supplied to the reaction chamber 131 of the reaction stage 130 by the inert gas supplied from the gas flow unit 120.

The step of synthesizing a compound by supplying the vaporized first precursor to the reaction chamber 131 of the reaction stage 130 in which the substrate 135 coated with the second precursor is embedded is the chalcogen precursor vaporized by an inert gas. It is supplied to the reaction chamber 131 through the supply port 133 of the reaction stage 130 and then reacted with the transition metal precursor coated on the substrate 135 in the reaction chamber 131 to synthesize a transition metal chalcogen compound.

At this time, the temperature within the reaction chamber 131 can be adjusted up to 1000°C.

The step of observing and photographing the nucleation and growth of the compound in the reaction chamber 131 in real time is the step of observing and photographing the nucleation and growth of the transition metal chalcogen compound through the observation window 132 provided in the reaction chamber 131 using the microscope unit 140. Nucleation and growth are observed and filmed in real time.

As described above, the microscope unit 140 includes a support portion 141 supporting the reaction stage 130, an objective lens 142 disposed opposite to the upper part of the observation window 132, and an objective lens 142. It includes an imaging module 143 that is arranged in-line to observe and photograph the nucleation and growth of the transition metal chalcogen compound in real time. And in this embodiment, the imaging module may be composed of a CCD camera 143.

Additionally, in this embodiment, it is possible to control physical properties such as defects and number of layers of the transition metal chalcogen compound using spectroscopic information. Accordingly, in this embodiment, in order to determine the number of layers of the transition metal chalcogen compound in the reaction chamber 131, a 620nm band-pass filter for monochromating light is mounted on the CCD camera 143, and the 285nm SiO ₂ /Si substrate 135 When observing the growth process of a transition metal chalcogen compound in real time, the contrast according to the number of layers can be measured.

Additionally, in this embodiment, Raman spectroscopy can be applied to determine defects in the transition metal chalcogen compound within the reaction chamber 131. Accordingly, the microscope unit 140 according to this embodiment includes a laser light source 145, a beam splitter 147 provided between the objective lens 142 and the imaging module 143, the beam splitter 147, and the laser light source 145. ), a collimator lens 146 provided between the beam splitter 147 and the imaging module 143, an imaging lens 148 provided between the imaging lens 148 and the imaging module 143, and a spectrometer (not shown) provided between the imaging lens 148 and the imaging module 143. ) may further be included. At this time, the CCD camera 143 can detect a Raman spectrum image.

In the step of displaying and storing the nucleation and growth of the captured compound, the image captured by the CCD camera 143 may be displayed on a display module 150 such as a monitor. And the image displayed on the display module 150 or the image captured by the CCD camera 143 may be stored in the control module.

The step of controlling the growth conditions of the compound by analyzing the growth process of the compound from the captured nucleation and growth image of the compound is controlling the growth conditions of the transition metal chalcogen compound, which includes the steps of controlling the temperature of the chalcogen precursor; , including controlling the temperature of the transition metal precursor and controlling the amount of inert gas.

Analyzing the growth of two-dimensional materials is very important in forming high-quality, large-area materials, but in the conventional case, ‘post-growth analysis’ was used, which had limitations in revealing the exact growth mechanism or actively controlling growth. The present invention can observe and analyze nucleation-growth, which is part of the growth of two-dimensional materials, in real time by using an integrated spectroscopic-growth platform that combines the chemical vapor deposition device and imaging technology necessary for the growth of two-dimensional materials. In other words, you can observe real-time growth over time, change growth factors through feedback, and observe changes in real time.

The spectroscopic-growth integrated platform of the present invention enables growth and real-time analysis of defects and number of layers, which are characteristics of two-dimensional materials, using real-time observation and imaging of the nucleation-growth process, allowing accurate analysis of the effects of growth conditions. there is. Through this, it is possible to overcome the low understanding of growth factors, which is a shortcoming of the conventional chemical vapor deposition method, and accelerate the understanding of the roles of various growth factors. It is expected that

That is, the integrated chemical vapor deposition microscope (ICVDM, 100) of the present invention can present the entire growth process (nucleation-growth-termination) of a two-dimensional material in a spectroscopic manner using imaging spectroscopy. , At the same time, the feedback of growth conditions can be implemented in real time. This easy feedback can enable real-time control of defects and number of layers during the growth process of two-dimensional materials and can be of great help in developing growth methods for various low-dimensional materials. In the following, we will look at the growth analysis of MoS ₂ , one of the two-dimensional materials, and the conditions for forming high-quality crystals.

The ICVDM of the present invention is capable of high-speed shooting up to 20 fps using a CCD camera 143, is capable of responding up to 1000°C, can control the atmosphere under various conditions (nitrogen, argon), etc., and has 100x magnification. The objective lens 142 can capture and store images of changes in nanomaterials of several micrometers depending on temperature, amount of precursor, time, etc.

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

Example 1. MoS using ICVDM ₂ Crystal size analysis according to nucleation and nuclear density

It is known that the process of changing MoO ₃ to MoS ₂ in the synthesis of transition metal chalcogens results from the MoO _3-x S _y form during the initial crystal nucleus formation process. Through real-time spectroscopy, a crystal size control method according to the nucleation density by processing the substrate 135 was derived.

Figure 6 is a diagram showing the process in which the nuclei of MoO ₃ change according to temperature after the start of the reaction in the integrated chemical vapor deposition microscope device according to the present invention, and Figure 7 is a diagram showing the process of nuclei according to the method of treating MoO ₃ on the substrate 135. It is a diagram showing the relationship between the density difference and the size of the crystal grains resulting from the difference, Figure 8 is a diagram showing the MoO ₃ precursor with uniform distribution obtained through sublimation, and Figure 9 is a diagram showing the number of nuclei versus the area of the crystal grains. am.

MoO depending on temperature ₃ Nuclear shape changes

Referring to FIG. 6, the nucleation of the transition metal chalcogen is accomplished from MoO ₃ as suggested in the conventional literature, and as the temperature is raised, a) it is spin-coated and exists in a flat form attached to the surface of the substrate 135. While b) it was confirmed that it melted at around 450 ^o C, which is lower than the melting point of MoO ₃ , which is 795 ^o C. c) When the temperature was further raised, MoO ₃ changed into a bead shape, and Ostwald ripening with the surrounding MoO ₃ occurred, confirming that the beads became larger. d) During the process of raising the temperature to the reaction temperature of 750 ^o C, the MoO ₃ beads became smaller through sublimation, and in the final process of nucleation, MoS ₂ began to grow while suddenly changing from a bead shape to a triangle shape.

MoO ₃ Nuclear density control and crystal size control method according to processing method

_SiO2 /Si The density of nuclei could be adjusted depending on the method of treating MoO ₃ on the substrate 135.

When MoO ₃ was prepared by dropcasting or spincoating a solution in which sodium cholate was added to MoO ₃ and dispersed in water onto the silicon substrate 135, it was found that the nuclear density was very low. On the other hand, in the case of the substrate 135 on which MoO ₃ was deposited, obtained by sublimating powdered MoO ₃ at high temperature, it was found that the nuclear density was very dense.

Referring to FIG. 7, crystal grains with a size of 30 μm or more were grown on the dropcast substrate 135 with a low nucleus density, and grains with a size of 10 μm or more were formed on the spincoated substrate 135 with a slightly higher nucleus density. Lastly, it was confirmed that in the deposited substrate 135, where the nucleus density is very dense, each crystal grain is merged to form a large-area MoS ₂ .

Figure 8 shows a MoO ₃ precursor with uniform distribution obtained through sublimation, and Figure 9 shows the number of nuclei versus the area of grains.

Example 2. MoS using ICVDM ₂ Crystal growth analysis

1) By changing the growth conditions (precursor temperature, amount of inert gas, etc.) of transition metal chalcogen compounds, changes in crystal orientation, shape, anisotropy, size, number of layers, etc. were examined in real time. Through ICVDM, a method of making crystals of a specific shape was discovered and the relationship between crystal shape and precursor amount was established. Defects that determine the properties of the synthesized material were analyzed through Raman spectroscopy, and the number of layers was analyzed through contrast measurement.

2) A method of analyzing the growth dynamics of growing grains was identified through ICVDM, and the surrounding atmosphere in which each grain grew was derived inversely.

Figure 10 is a diagram showing contrast images of various MoS ₂ crystals by layer number when determining the number of layers of a MoS ₂ crystal using an optical contrast measurement method, and Figure 11 is a diagram showing the number of layers of a MoS ₂ crystal using an optical contrast measurement method. It is a diagram showing the correlation between the number of layers and optical contrast, and Figure 12 is a diagram showing the control of the temperature ( T _MoO3 , T _S ) of each precursor and the flow rate of inert gas ( F _Ar ) during the growth process of _{MoS 2} according to growth time. , Figure 13 is a diagram showing the contour lines of MoS ₂ outline according to growth time during the growth process of MoS ₂ according to growth time, and Figure 14 is a diagram showing images of MoS _{2 crystal growth by time during the growth process of MoS 2 according} to growth time. 15 is a diagram showing a graph fitted with data obtained by measuring the length of the vertex or side from the center of the triangular grain of MoS ₂ crystal growth over time during the growth process of MoS ₂ according to growth time, and Figure 16 is a graph fitting the It is a diagram showing that grains grow through oscillation through the difference between the fitting graph and the actual graph during the growth process of MoS ₂ , and Figure 17 shows the change in shape according to the equivalence of Mo and S in the MoS ₂ plane. Figure 18 is a diagram showing the shape of the MoS ₂ crystal according to the partial pressure of each precursor through kinetic Monte Carlo simulation, and Figure 19 is a diagram showing the relationship between the experimental partial pressure and the shape of MoS ₂ formed.

Real-time floor analysis using optical contrast

As shown in FIGS. 10 and 11 using ICVDM, MoS ₂ grown in various layer numbers was subjected to optical contrast imaging using a CCD camera 143 to derive a discrimination method for each layer number. In the case of MoS ₂ synthesized by chemical vapor deposition, it was found that the method of determining the number of layers using contrast optical imaging showed high reliability, and this method was applied during real-time measurement.

Transition metal chalcogen layer number using an integrated platform in situ decision analysis

The contrast causes constructive/destructive interference depending on the number of layers and the SiO ₂ thickness of the substrate 135 itself. We present a spectroscopic method that allows you to immediately determine the number of layers while observing the growth process of MoS ₂ in real time using an integrated platform. For this purpose, the light was monochromatized using a 620nm band-pass filter, and the contrast according to the number of layers was measured on a 285nm SiO ₂ /Si substrate (135).

As can be seen in Figures 10 and 11, the number of layers and contrast have a direct correlation, and the number of MoS ₂ layers having 1 to 5 layers could be determined in real time.

Triangular MoS obtained by ICVDM ₂ Observation and analysis of crystal growth dynamics

The growth of MoS ₂ triangular grains was observed in real time using ICVDM according to the present invention.

As shown in FIG. 12, the growth conditions control the temperature of the sulfur (S) and MoO ₃ precursors and Ar flow ( F _Ar ), and the temperature of the reaction chamber 131 used for chemical vapor deposition is set to 750 ^o C. So we proceeded. In general, growth was terminated within a few minutes after reaching 750 ^o C, as shown in Figures 13 and 14. Figure 13 is a colored image of the outline of MoS ₂ triangular crystal grains per second, and it was confirmed that the growth rate slows down as it grows. In addition, as shown in FIG. 12, the process was conducted at 750 ^o C in an inert gas Ar atmosphere, and one image per second was obtained through the CCD camera 143. Using these image stacks, we were able to analyze growth dynamics.

Figure 15 is the result of fitting the growth trajectory based on the sides and vertices. Growth could be fitted with a curve of the form G (t)= ντ [1-exp(- t / τ )]. At this time, G(t) is the length from the center of the grain to the side and vertex over time, ν is the initial growth rate, τ is the time constant of the reaction, and t is the time for the reaction to proceed. The initial growth rate ν of the vertices and sides was measured to be around 1 and 0.5 μm. Figure 16 is a graph showing the periodic difference between data obtained by actual measurement and data obtained by fitting. The periodic difference between the actual growth curve and the fitted curve could be expressed as Δ G ( t )=-0.39exp(- t /47)×sin(π( t - t ₀ )/15.2), which is a sine damp form equation. Through this, it was confirmed that the growth speed of one side of the triangular crystal grain was not constant, but grew with a period of 30.4 seconds. This periodicity is observed in solid synthesis using solid-vapor-solid (SVS) phase transformation and is believed to be formed due to the relationship between current growth and partial pressure. The curve, which starts with a positive value during nucleation, starts with a negative value during etching, suggesting that the characteristic is related to partial pressure, and it was found that crystal growth is induced through the oscillation of partial pressure (see Figure 16). .

Meanwhile, as the temperature of the miniaturized heating furnace 110 increases, a hot gas film is formed between the heating furnace 110 and the substrate 135, causing a slight drift of the sample over time. To correct this phenomenon, changes in growth according to time and growth conditions were observed using ImageJ's image stabilizer. In addition, in order to examine the synthesis dynamics of MoS ₂ over time, color-coded growth dynamics were presented using image stacks and computational functions, as shown in Figure 13.

MoS ₂ Synthetic analysis of different crystal forms using simultaneous regulation of growth factors

The growth factors of MoS ₂ that can _be controlled in the ICVDM of the present invention include the temperature of the MoO ₃ precursor ( T _MoO3 ), the temperature of the S precursor ( TS ), and the flow rate of Ar to be used as a delivery gas for S ( F _Ar ) (FIG. 12 reference). Typical growth conditions for growing triangular grains of MoS ₂ are T _MoO3 = 750 ^o C, T _S = 250 ^o C, F _Ar = 20 sccm. The effects of growth factors are analyzed through growth-etching images obtained by adjusting these factors one by one in a single experiment, and the resulting correlation with crystal form is presented. In a similar form, hexagonal MoS ₂ grains are obtained under the conditions of T _MoO3 = 830 ^o C, T _S = 280 ^o C, and F _Ar = 20 sccm.

Figure 17 shows the change in shape according to the equivalence of Mo and S in the MoS ₂ plane. In the case of ideal Mo:S = 1:2, ZZ _s (or ZZ _Mo ) occupies each line segment of the hexagon, and Mo:S When =1:>2, ZZ _Mo due to S excess forms a line segment of a triangle. Figure 18 shows the MoS ₂ crystal shape according to the partial pressure of each precursor through kinetic Monte Carlo simulation. In addition, the partial pressures of MoO ₃ and S according to each form are as shown in FIG. 19. This result can be obtained through real-time observation by adjusting the flow rate.

MoS through derivation of equivalence map of precursor ₂ Shape control method

To establish a growth model, the growth and etching processes were analyzed by applying kinetic Wulff construction, a solid-state chemistry model, based on growth with minimum surface energy. In particular, during the growth process of MoS ₂ , the flow of S was stopped and the etching of crystal grains was induced, and the etching rate derived during this process was calculated based on the assumption that the behavior of the precursors, S and Mo, were ideal gases, taking into account the molecular frequency, activation energy, and temperature. The escape rate (r _esc ) could be determined using the following formula. r _esc = ν exp(- E _e,Mo / k _B T ) where ν is the frequency of the elements constituting the crystal lattice (~10 ¹³ s ^-1 ), and E _e,Mo is the frequency required to separate Mo from the crystal lattice. is the activation energy, k _B is the Boltzmann constant, and T is the absolute temperature. The partial pressure of each precursor can be derived from the escape rate of atoms formed under specific temperature conditions. Using this _, the partial pressure conditions (i.e. P _S , P _MoO3 ) of the precursor formed at each temperature can be analyzed, and based on this analysis, the P _MoO3 : PS ratio that forms a hexagonal crystal can be obtained and an experimental equivalence map can be drawn ( 19). Based on this, the equivalence point with a mole fraction of Mo:S=1:2 was identified.

As such, the present invention is not limited to the described embodiments, and it is obvious to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the present invention. Accordingly, such modifications or variations should be considered to fall within the scope of the claims of the present invention.

100: Integrated chemical vapor deposition microscope device 110: Heating furnace
120: gas flow unit 130: reaction stage
140: Microscope unit 150: Display module
160: control unit 170: optical table

Claims (14)

A heating furnace for vaporizing the first precursor;
a gas flow unit provided in communication with the heating furnace and controlling the amount of inert gas supplied to the heating furnace;
a reaction chamber containing a substrate supplied with the vaporized first precursor carried by the inert gas and coated with a second precursor reacting with the first precursor; and an observation window provided in the reaction chamber, wherein temperature is controlled. This possible reaction stage; and
An integrated chemical vapor deposition microscopy device including a microscope unit disposed opposite the observation window to observe and photograph the nucleation and growth of the compound synthesized by the first precursor and the second precursor in the reaction chamber in real time. . According to paragraph 1,
The microscope unit is,
a support portion supporting the reaction stage;
An objective lens disposed opposite the observation window; and
An integrated chemical vapor deposition microscopy device including an imaging module disposed in-line with the objective lens to observe and photograph nucleation and growth of the compound in real time. According to paragraph 2,
The imaging module is an integrated chemical vapor deposition microscope device including a CCD camera (Charge Coupled Device camera). According to paragraph 3,
An integrated chemical vapor deposition microscope device in which the CCD camera is equipped with a bandpass filter to monochromatize light. According to paragraph 2,
The microscope unit is,
light source;
A beam splitter provided between the objective lens and the imaging module;
a collimator lens provided between the beam splitter and the light source;
An imaging lens provided between the beam splitter and the imaging module;
An integrated chemical vapor deposition microscope device further comprising a spectroscope provided between the imaging lens and the imaging module. According to paragraph 2,
An integrated chemical vapor deposition microscopy device further comprising a display module connected to the imaging module to display nucleation and growth of the compound. According to paragraph 1,
Connected to the heating furnace, the gas flow unit, the reaction stage, and the microscope unit, the captured nucleation and growth images of the compound are stored, the growth process of the compound is analyzed, and the temperature of the first precursor and the An integrated chemical vapor deposition microscopy device further comprising a control unit that controls growth conditions of the compound by controlling the temperature of the second precursor and the amount of the inert gas. According to paragraph 1,
An integrated chemical vapor deposition microscope device further comprising a vibration-free optical table on which the gas flow unit, the reaction stage, and the microscope unit are fixed. According to paragraph 1,
The first precursor is a chalcogen precursor, and the chalcogen precursor is at least one element selected from the group consisting of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te), or a compound containing these elements Includes,
The second precursor is a transition metal precursor, and the transition metal precursor is molybdenum (Mo), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), An integrated chemical vapor deposition microscope device that is a compound containing at least one selected from the group consisting of cobalt (Co), nickel (Ni), niobium (Nb), and tungsten (W). (a) vaporizing the first precursor;
(b) supplying the vaporized first precursor to a reaction chamber of a reaction stage containing a substrate coated with the second precursor to synthesize a compound;
(c) observing and photographing the nucleation and growth of the compound in the reaction chamber in real time; and
(d) A method for controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscopy device, including the step of controlling the growth conditions of the compound by analyzing the growth process of the compound from the captured nucleation and growth image of the compound. . According to clause 10,
In step (d),
adjusting the temperature of the first precursor;
adjusting the temperature of the second precursor; and
A method for controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscope device, including the step of controlling the amount of the inert gas. According to clause 10,
In step (c),
A method for controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscope device that observes and photographs the nucleation and growth of the compound in real time through an observation window provided in the reaction chamber using a microscope unit. According to clause 12,
The microscope unit is,
a support portion supporting the reaction stage;
An objective lens disposed opposite the observation window; and
A method for controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscope device including an imaging module disposed in-line with the objective lens to observe and photograph nucleation and growth of the compound. According to clause 10,
(e) A method for controlling the synthesis of low-dimensional materials using an integrated chemical vapor deposition microscopy device, further comprising the step of displaying and storing the nucleation and growth of the compound photographed in step (c).