KR20160006637A - X-ray Penetration Analysis Method of Extreme Super-Thin Graphene - Google Patents

Abstract

The present invention relates to an X-ray penetration analysis method for analyzing an ultrafine thin film remaining in an unknown area so far. The X-ray penetration analysis method includes: (a) a step of preparing: a chamber on which a sample is mounted and which is controlled in 278-328 °K of a temperature condition and less than 70% of a humidity condition; a parallel beam X-ray radiation device radiating an X-ray onto the sample in the chamber; and a detection device detecting the X-ray penetrating the sample in the chamber; (b) a step of etching a substrate on a graphene sample in which graphene of first to tenth layers is combined with the substrate of 0.3×0.3 cm or greater in the chamber and mounting the graphene sample formed to penetrate the graphene on a sample holder to prevent influence in the penetration of the X-ray; and (c) a step of detecting and analyzing the X-ray by the detection device by radiating the X-ray onto the graphene sample by the parallel beam X-ray radiation device.

Description

Technical Field [0001] The present invention relates to an X-ray penetration analysis method for graphen having a very fine thickness,

The present invention relates to an X-ray transmission analysis method for analyzing a very thin film which has remained as an unknown region.

X-ray analysis methods for materials are very important. Representative x-ray analysis methods include x-ray scattering, x-ray reflection, x-ray absorption, x-ray fluorescence, x-ray morphology and topology analysis (imaging), and x-ray diffraction. Recent advances in equipment technology are enabling x-ray analysis of thin films of several nm thickness and nanograms of a few nanometers in size. However, it is believed that a single crystal film of about 3 nm or less and an ultra-fine thickness of 2 to 3 nm or a nanograin analysis method of extreme size is very difficult with current x-ray analysis technology, and it is becoming a next technology roadmap to overcome this. This roadmap is very important. In other words, it is possible to study the application of these materials as new materials through the analysis of extreme thin films between 0.5 and 3 nm in thickness. Since their physical properties provide a link between atoms / molecules and existing nanomaterials (thickness dependence and Size effect), it is possible to study the origins of the manifestation of material properties.

0.5 to 3 nm in thickness The difficulty of X-ray analysis on the crystalline film is due to the following four reasons.

(1) Difficulty in preparing specimens (requiring high manufacturing skills and low reliability / low reproducibility for manufactured specimens)

(2) Changes in specimen and contamination (such as oxidation) due to thermodynamic instability of specimen

(3) difficulty in identifying the change and contamination and grasping the degree of change (degree of pollution)

(4) Limitations of X-ray analyzer and absence of X-ray analysis method

The reason (1) will be described in detail as follows.

Whether thin films or nanoparticles, nuclei are formed by nucleation of atomic and molecular elements, and these nuclei are grown through collision. At this time, the minimum nucleus size, that is, the minimum nanoparticle size, is at least 3 nm. That is, it is very difficult to obtain nanoparticles of 3 nm or less. This is due to the volatile nature of the growth in larger form, and the thermodynamic stability of the nanoparticles is largely dependent on the size of the particles (this is also related to reason (2) above).

The reason for the above (2) will be described in detail as follows.

Nanoparticles or nanotubes of 3 nm or less are extremely unstable thermodynamically, so that they have a low thermal energy (many samples spontaneously change even at room temperature) and high reactivity to humidity, resulting in a change or a completely different state. This can lead to changes during X-ray measurement. Therefore, in the case of the ultimate thin film, the inherent physical properties are lost, and the result is not produced or the result is erroneous.

The reason (3) will be described in detail as follows.

(I) environmental factors (temperature and humidity), (ii) environmental factors (temperature and humidity), and environmental conditions (temperature and humidity) , (Ii) measurement factors (device components and measurement methods), and (iii) specimen specifications (size, thickness, shape, etc.). Therefore, it is very difficult to test the degree of variation of the specimen and the degree of contamination.

The reason (4) will be described in detail as follows.

It is extremely difficult to analyze ultrafine thin film and ultrafine nanoparticles because of the insufficient comprehensive analysis tools including X-ray beam, X-ray irradiation method, detector type, detection method, and substrate influence consideration. For example, when an X-ray is irradiated on an ultramaf thin film, information on the target thin film on the upper layer is not displayed at all and only information about the substrate is obtained. This is a natural feature of the x-ray beam with very high penetrating power (see X-rays measuring the bones of the body).

Graphene as an ultimate thin film is a new material with 1 to 10 layers (thickness less than 3 nm) in which quantum mechanical properties can be expressed (property distinguishing it from graphite and nano carbon). Graphene has excellent electrical properties, mechanical strength and thermal conductivity, and plays a major role in materials and academic fields.

Graphene can be divided into two types of powdered graphene obtained by physical chemical separation of thin film graphene produced by thermal decomposition deposition (CVD method) of hydrocarbons and graphite. Each time the number of graphene layers increases, electronic structure and quantum mechanical properties are changed and new properties are expressed. Therefore it is very important to know the number of graphene layers and to study the properties by layer number.

However, there are few reports of XRD diffraction of thin film graphene of 10 layers or less. Usually, the layer number analysis is performed using a local Raman analysis method and an electron microscopic method in the micrometer region. This is because the reliability is low, Is far from the crystallographic analysis of graphene, which is the first obstacle to the commercialization of graphene. It is very serious to discuss the total number of graphene layers and their thickness with about one millionth of the data, as it is a very big mistake to analyze the thickness of only a small part of the ice sheet and judge that the entire ice sheet is safe. And there is no realistic alternative.

In the case of thin-film graphenes, the technique of making a uniform one-layer has considerable reliability, typically made of roll-to-roll (R2R) over large area copper (Cu) foil. The single-layer film graphene is removed from the copper foil by etching and the like. The technique of transferring to a desired substrate by attaching to a polymer such as PDMS, that is, transfer technology, has been greatly developed and is currently in the commercial stage. However, when the graphene is exposed to air without a protective film, there arises a problem that oxidation reaction (-OH formation) and crystal destruction by graphene interlayer oxygen and moisture impregnation occur.

However, currently, multi-layered film graphenes having two or more layers can not be reliably produced because, when another carbon source is grown on the single-layer film graphene, the degree of freedom in the vertical direction of the carbon- (Entropy increase, degree of freedom increase) layer number control becomes impossible. That is, the manufacturing mechanism of the multi-layered film graphene film is different from the single-layer film graphene manufacturing process in which Cu-C bonding is maximally induced. For this reason, studies on the physical properties of graphene layers are insignificant. Naturally, no method for measuring the number of graphene layers has been developed.

On the other hand, graphene powder is usually formed of a multilayer film because it is produced by peeling graphite, but the number of layers such as the edge portion, the edge portion, and the center portion are all different. In other words, even in one graphene powder having a two-dimensional planar structure, the distribution of the number of layers is different. The distribution of the number of layers between the graphene powders is also different. Of course, no measuring method has been developed to determine the average number of graphene layers or the number of layers in the entire powder.

Since the graphene layer number evaluation (measurement) method has not been developed, graphene production and graphene commercialization have become a major obstacle. In order to commercialize graphene powder, You should be able to produce powders in tonnes, but you need to immediately know the average number of layers (or thickness) for at least 1 mg (about 10 ⁵ ) in the manufacturing process, so that by repeating the sampling test on the mass- ¹¹ ), and the average graphene layer number for 1 ton (about 10 ¹⁴ ) can be evaluated. Also, since the manufacturing process can be reviewed again from the analysis results, the method of evaluating the number of layers of graphene is very important in industry.

X-ray diffraction is a method of analyzing diffracted X-rays satisfying the Bragg's law (Bragg's law (Cullity, 1978)) on a specific crystal plane with respect to an incident X-ray and expressed by the following formula 1 .

[Equation 1] n? = 2d _{( hkl )} sin?

Where λ is the X-ray wavelength, θ is the diffraction angle, n is the order of the diffraction peak expressed as an integer, d is the interplanar spacing of the lattice, and (hkl) is the Miller index of the crystal plane.

The thickness of the crystal plane by Sherrer's equation (Cullity, 1978) is expressed by [Equation 2] below.

[Equation 2] D = K? / B cos?

Where D is the thickness of the crystal face, K is a constant (typically 0.89) depending on the shape of the crystal grain,? Is the X-ray wavelength, B is the full width at half maximum (FWHM), and? Is the diffraction angle.

The approximate thickness of the graphene crystals is 1 layer (3.5 Å or less), 2 layers (~ 7 Å), 3 layers (~ 10.5 Å), 4 layers (~ 14 Å), 5 layers (~ 24 Å) and 7 layers (~ 24 Å), and the XRD measurement method can not obtain a peak and there is almost no XRD study on them. A study on X-ray transmission analysis of graphene crystals There is no such thing.

An object of the present invention is to provide an X-ray transmission analysis method for graphene having a very fine thickness.

In order to solve the above problems, the present invention solves the above problems by using ultra-thin film graphene, which is a kind of extreme ultra thin film material. In addition, seven candidate specimens with a clear thickness definition and a thickness difference of about 3.5 nm were derived and the X - ray analysis method was established.

(1) Specially derived ultra-thin film graphene specimens are composed of one layer (3.5 Å or less), 2 layers (~ 7 Å), 3 layers (~ 10.5 Å), 4 layers (~ 14 Å) , 6 layers (~ 21 Å), and 7 layers (~ 24.5 Å).

(2) The temperature and humidity, which are environmental factors of the ultrafine film graphene specimen, should be maintained at 278 ~ 328 Kelvin (5 ~ 55 ℃) and humidity less than 70%, and if this condition is exceeded, Lt; / RTI >

(3) The specification of the graphene specimen is 1 to 10 layers of graphene in the present invention, and the size of the specimen is 0.3 cm x 0.3 cm or more.

(4) The X-ray irradiator, which is indispensable within the above-mentioned conditions, may be a parallel beam X-ray optics, an Array type detector, a ω-2θ measuring method, a rocking curve measuring method, Detector rotation method, graphene transmission x-ray, x-ray crystal diffraction method of graphene crystal, diffraction method of graphene (002) specific crystal plane, and all components of x-ray diffraction device.

Therefore, X-ray analysis of ultra-thin film graphene is possible if the above conditions are satisfied.

Particularly, in order to perform the transmission analysis on the graphene specimen, the graphene specimen must be processed in a state in which the X-ray is transmittable, and the specimen holder for laying the graphene specimen should also be constructed so as not to affect the X-ray transmission.

Accordingly, the present invention provides: (a) a chamber controlled to a temperature condition of 278 to 328 ° K and a humidity condition of less than 70%, a chamber in which a specimen is placed, a parallel beam X-ray irradiating device for irradiating the specimen in the chamber with X- Preparing an X-ray analyzing apparatus comprising a detecting device for detecting X-rays passing through the specimen; (b) removing a part or all of the substrate in a state where a graphene film of 1 to 10 layers is bonded to a substrate having a size of 0.3 x 0.3 cm or more in the chamber, and a graphene specimen configured to transmit X- Placing on a specimen table configured to not affect the transmission of the line; (c) irradiating X-rays to the graphene specimen with the parallel beam X-ray irradiator to detect and analyze X-rays transmitted through the detector; Quot; X-ray transmission analysis method for graphen having a very fine thickness ".

As the graphene specimen, a specimen (hereinafter, referred to as an A type specimen) from which a part of the substrate was removed through etching (hereinafter, referred to as a 'B type specimen' (Hereinafter, referred to as 'C type specimen') transferred onto a substrate, a mesh, or a porous substrate, and a specimen prepared by etching the transfer substrate of the C type specimen (hereinafter referred to as 'D type specimen' Can be applied.

In addition, the present invention is characterized in that the step (a) further comprises the step of preparing a second detecting device for detecting X-rays reflected by the graphene specimen without X-rays transmitted therethrough, X-ray irradiation angle in the X-ray irradiator and the arrangement of the second detector are set in the 2? (Theta) -ω (omega) method. "Together.

Here, in the step (c), the angle of the X-ray irradiated to the graphene specimen may be set within a range derived from the following [irradiation angle derivation formula].

[Investigation angle derivation expression]

X-ray irradiation angle = (2? _{( Hkl )} 2) 占 1 占

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

In the step (c), the second detecting device may be installed within an angle range derived from the following [detection angular expression] based on the graphene specimen.

[Detection angle derivation expression]

X-ray detection angle = (2? _{( Hkl )} ? 2) 占 1

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

The graphenes of the present invention can be produced by graphene produced by the CVD method and graphene or modifier graphene obtained by physically, mechanically, electrochemically or chemically modifying them, graphene graphene, Chemically oxidized graphite oxide (a kind of graphene) or graphene oxide, graphite oxide or graphene oxide thermally reduced graphene and chemically reduced graphene, expanded graphene (intercalated carbon compound) Graphene nanoplate manufactured from a material which is expanded by thermal or microwave or energy application), graphene which is peeled graphitically by using physicochemical or solvent, graphene produced by top down type, Pin, graphene produced on the basis of catalyst, graphene prepared through decomposition of hydrocarbon, surface of SiC Graphene formed, graphene encapsulated on the surface of nanoparticles, RGO, and modi fi ed graphene nanoflates that are physically, chemically, and electrically modified in graphene nanoplate.

Also, since it is known that oxygen exists unconditionally on the surface of graphene, the graphene of the present invention has an oxygen content of 5% or less, and sulfur and phosphorus components may be contained by 5% or less through chemical oxidation of graphite have.

Also, the graphenes of the present invention may be doped with elements such as boron, phosphorus, sulfur, nitrogen, and fluorine through a conventional doping process.

Also, the graphenes of the present invention may have various groups on the graphene surface through additional chemical reaction, surface treatment or post-treatment, and OH, -COOH, -CONH ₂ , -NH ₂ , -COO- , -SO ₃ -, -NR ³⁺ , -CH═O, C-OH,> O, CX and the like.

The graphene materials of the present invention can be further added in various forms. The criteria of the present invention include surface oxidizing groups, functional groups, functional groups, degree of defect in basal plane, modified functional group, doping element, Regardless of the number of basal planes from 1 to 10 layers.

According to the present invention, crystallographic information can be obtained through X-ray transmission analysis of ultrafine thin films of 3 nm or less or ultrafine thin film graphenes having 1 to 10 layers of layers which can not be performed previously. As the analysis of physical properties becomes possible, industrial applications of graphene, which is regarded as a new generation of new materials, becomes possible. The crystallographic and layer number information of the unknown graphene can be obtained by using these X-ray analysis information as a reference. This makes it clear that the basic specifications (number of layers, thickness, etc.) of graphene materials, which have not been clear in the meantime, will greatly enhance the diversity and certainty of future graphene products, reliability of finished products and product competitiveness.

FIG. 1 is a schematic diagram of an X-ray analyzer applied to the present invention. FIG.
[Figure 2] and [Figure 3] are schematic diagrams of another X-ray analyzer.
[Fig. 4] is a schematic diagram showing that the X-ray irradiation angle and the position of the X-ray diffracted from the ultra-thin film graphene on the X-ray opaque substrate are all located in the semisphere of the upper part of the specimen.
[Fig. 5] is a schematic diagram showing that an X-ray irradiation angle with respect to an ultra-thin film graphene on a transmissive substrate and a position of an X-ray emitted from the ultrasensitive ultra-thin film graft on the transmissive substrate are both located in the semisphere of the lower specimen.
6 is a graph showing the relationship between the X-ray irradiation angle and the position of the X-ray transmitted or diffracted from the ultrathin ultra-thin film graphene on the transmissive type substrate by the semispheres of the upper half of the specimen and the three- In which all the rotated X-rays are located.
[Fig. 7] is a schematic diagram of a method of producing X-ray transmission type graphene or X-ray transmission type graphene specimen.
[Fig. 8] is a schematic diagram of a method of fixing and treating a graphene specimen.
[Figure 9] is an XRD pattern graph of a sample prepared by laminating a single-layer graphene thin film from 1 to 10 layers by a transfer method (a silicon oxide film is formed on a 1 cm x 1 cm silicon substrate in order to improve the flatness ratio, S1 to S10 are the names of each sample).
10 is a data value in which the (002) peak of FIG. 9 is analyzed and shown in a table.
11 is a value obtained by analyzing the data of FIG. 10 and determining the absolute number of graphene layers for the samples S1 to S10.
FIG. 12 is a graph comparing the values of FIG. 11 with the theoretical values.
[Fig. 13] is a graph showing the (hkl) peak of the seven-layer graphene found using the GI SAXS method.
14 is a rocking curve graph showing the orientation of graphene crystals. FIG.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

(A) a chamber controlled at a temperature condition of 278 to 328 K and a humidity condition of less than 70%, a chamber in which a specimen is placed, a parallel beam X-ray irradiating device for irradiating the specimen in the chamber with X- Ray detector and a detector for detecting X-rays passing through the X-ray analyzer; (b) removing a part or all of the substrate in a state where a graphene film of 1 to 10 layers is bonded to a substrate having a size of 0.3 x 0.3 cm or more in the chamber, and a graphene specimen configured to transmit X- Placing on a specimen table configured to not affect the transmission of the line; (c) irradiating X-rays to the graphene specimen with the parallel beam X-ray irradiator to detect and analyze X-rays transmitted through the detector; X-ray transmission analysis method for graphene having a very fine thickness. The temperature condition and the humidity condition of the chamber will be described later.

In the chamber, a specimen to be analyzed is placed. The specimen to be analyzed applied to the present invention is a graphene specimen to which a graphene film of 1 to 10 layers is bonded to a substrate having a size of 0.3 x 0.3 cm or more. The graphene specimen may be configured such that part or all of the substrate is removed so that X-rays are transmitted through the graphene. In this case, the specimen holder for holding the graphene specimen should also be configured so that it does not affect the X-ray transmission (in some cases, for example).

The graphene specimen for X-ray permeability analysis is a specimen (hereinafter, referred to as "A type specimen") in which a part of the substrate is removed while a graphene film is bonded to the substrate, a specimen (Hereinafter, referred to as a 'C type specimen') transferred from the B type specimen to a mesh or porous substrate and a specimen prepared by removing a part of the transfer substrate of the C type specimen (hereinafter referred to as' D type specimen ").

In addition, the graphene specimen may be prepared by physically placing a graphene film prepared in advance on a substrate from which a part of the plate surface has been removed.

When applying a specimen using an X-ray transmission type substrate, the material, thickness and transmittance of the substrate should be confirmed. As the X-ray transmission type substrate, a plastic substrate, a ceramic substrate, a porous substrate, and a fiber composite substrate can be selected, and the transmittance according to the thickness of the substrate can be checked before application. Various methods for producing graphene specimens using an X-ray transmission type substrate are shown in FIG.

[Fig. 7] (a) schematically shows a method for producing a graphene sample using CVD graphene. As described above, the A type specimen or the D type specimen can be applied to transmit X-rays.

7 (b) schematically shows examples of the graphene specimen in which the specimen has physically placed the graphene film prepared in advance on the substrate from which a part of the flat surface has been removed. That is, in the case of graphene powder, the graphene film (E type) is prepared in advance by pressing the powder itself (maintaining the film shape by the interlayer bonding force), and the graphene film A specimen (G type) on which the graphene film is laid, etc. can be obtained on a specimen (F type), a mesh substrate, a porous substrate, an etched substrate, etc., and a specimen (H type) It is possible. The graphene powders used here include graphene doped with less than 5% oxygen, thermally reduced graphene, chemically reduced graphene, graphene oxide (such as surface oxidizing and modified substituents), ball milling results of graphite, Energy ball milling results, chemically reactive ball milling (ball milling + chemical reactions (liquid and vapor), ball milling + carbon dioxide reaction, etc.), and graphene nanoplates made from expanded graphite. The graphene or graphene oxide containing an oxidizing group can be thermally treated separately to best observe the moment of change of the graphene (002) crystal face.

FIG. 8 shows a method of placing a graphene specimen in a chamber. Graphene specimens can be fixed on a specimen holder and physical methods (crimping, pressing, etc.). Mechanical methods (screws, etc.), chemical methods (adhesives, pastes, etc.), electromagnetic methods (electrostatic attraction, electrostatic film, etc.) can be applied and fixed by van der Waals force or magnetic force.

The X-ray analysis apparatus provided by the present invention may be provided with a heat treatment apparatus for applying heat to the graphene specimen in the chamber. After the liquid graphene dispersion is coated on the substrate, the excess solvent or adsorbed solvent can be removed while being lightly heat treated by the heat treatment apparatus. Also, even if the graphene specimen is susceptible to moisture adsorption or to prevent moisture adsorption, it can be heated within a stable temperature range through the heat treatment apparatus. In addition, the graphene (002) plane can be directly observed while the graphene or graphen oxide materials containing an oxygen group are heat-treated by the above-described heat treatment apparatus. For example, when the graphene oxide was coated on a glass substrate and subjected to heat treatment at 50 ° C to remove excess moisture, the (002) crystal face was located at 2θ = 11.5 ° when measured by the 2θ-ω method. As a result of heat treatment at 230 ℃, it was observed that 2θ = 23.3 ℃.

FIG. 8 (c) is a concept designed to maximize the effect of changing the physical properties of the ultra-thin plate graphene specimen. It has been found that grafting of graphene does not break the intergranular bond inside graphene even if it is increased to about 30%, but there is no XRD study yet. Therefore, a fixing unit (fastening type or the like) for gripping and fixing the graphene specimen as shown in FIG. 8 (c) can be provided on the edge of the graphene specimen in two or four directions, Or the four fixed portions may be configured so that the two opposing portions behave as a pair. That is, it is possible to provide a micro-stretching apparatus for holding the graphene specimen and fixing the pair of opposed fixing units in micro units.

The micro-stretching apparatus may be embodied as a device capable of pulling out by using an ultrafine mechanical device and a device capable of pulling out by using a piezoelectric material. As a simple example, a CVD 5-layer graphene specimen transferred onto a PET film was placed on a metal plate, and a PET film protective film was placed on the upper end portion of both sides of the specimen (above the side surface of the graphene) . As a result of X-ray diffraction measurement at one side (about 5%) (PET + graphene as a whole), it was found that the interlayer spacing increased about 3 to 8% after stretching because the quality of graphene crystals deteriorated due to stretching can do.

S1 to S10 samples

Samples S1 to S10 shown in Fig. 9 are specimens obtained by transferring single-layer film graphenes and laminating layers 1 to 10. In order to improve the flatness of graphene crystals, a silicon oxide film is formed on a 1 cm × 1 cm silicon substrate and graphene is transferred thereon. The sample names were named S1 ~ S10 according to the number of layers stacked.

The graphenes physically layered (layer by layer) in the S1 to S10 samples do not form graphene crystals having the same number of layers. The number of physically stacked graphene layers may be equal to or different from the number of layers actually forming crystals (when there is a spatially excited state without forming crystals, the number of stacked layers and the number of crystal layers are different) .

Also, since the lamination process is performed manually at present, there is a high probability that graphene crystals having different numbers of layers are formed in each process even if the same number of layers are stacked. Therefore, the method of measuring the number of graphene layers proposed in the present invention is also necessary in this respect.

Analysis of the XRD patterns for the samples S1 to S10 indicated that the number of graphene layers of each sample was not identical to the number of times of lamination (for example, the number of graphene layers of the S10 sample was 7). As a result of purchasing the same kind of sample from the same manufacturer, it was concluded that the number of layers of graphene crystals can not be known only by graphene layer recovery because the number of layers of graphene was analyzed differently.

In conclusion, [Figure 9] shows the results of X-ray diffraction analysis of crystals according to thickness of graphene, which is one of the world's first extreme thin films. It provides absolute physical quantities by the number of graphene layers as well as their physical properties, and suggests a way to use them as a reference at any time in the world.

In the step (c) of the present invention, the X-ray diffracted by the Bragg rule can be analyzed. However, a direct transmission type x-ray diffracted by Bragg's law, absorbed x-ray elastic scattering, and inelastic scattering analysis methods are also applicable. For example, X-rays may be irradiated to graphene at a predetermined angle of incidence that does not fit the Bragg rule (ie, perpendicular to the plane of the graphene specimen plane), and the detector may be placed on the opposite side to analyze X-rays emitted directly.

As a concrete example, the graphene specimens S3 to S6 (the numbers indicate the number of layers of graphene) showed an X-ray absorptivity of 0.5 to 1% per graphene layer, not only due to diffraction factors, It is a result showing the physical properties. Future research Further research by number of layers and number of layers is required.

When X-rays are transmitted through any one of the A-type specimen and the D-type specimen, a part of the X-ray can be reflected by the graphene film even if the X-ray penetrates the graphene film of the graphene specimen or is absorbed into the graphene film.

According to the present invention, in the step (a), a second detecting device for detecting X-rays reflected by the graphene specimen after being irradiated with X-rays can not be transmitted, and the step (c) X-ray irradiation angle in the X-ray irradiator and the arrangement of the second detector are set in the 2? (Theta) -ω (omega) method. "Together. Thus, most of the transmitted X-rays can be analyzed and some of the reflected X-rays can be analyzed together.

Here, in the step (c), the angle of the X-ray irradiated to the graphene specimen may be set within a range derived from the following [irradiation angle derivation formula].

[Investigation angle derivation expression]

X-ray irradiation angle = (2? _{( Hkl )} 2) 占 1 占

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

In the step (c), the second detecting device may be installed within an angle range derived from the following [detection angular expression] based on the graphene specimen.

[Detection angle derivation expression]

X-ray detection angle = (2? _{( Hkl )} ? 2) 占 1

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

On the other hand, the specimen holder can be configured to pivot the specimen in three axial directions (x-y-z axis). [Reference Fig. 1] below is a schematic diagram of a specimen rotating about three axes.

[Reference Figure 1]

In addition, the parallel beam X-ray irradiating device may be configured to perform centrifugal rotation in the longitudinal direction and in the transverse direction, and the detecting device may be configured to rotate centrifugally in the longitudinal direction and the transverse direction. [Refer to Fig. 2] below is a schematic diagram of the centrifugal rotation of the parallel beam X-ray irradiating device and the detecting device in the longitudinal direction and the transverse direction.

[Reference Figure 2]

FIG. 1 is a schematic diagram of an X-ray analyzer provided by the present invention. FIG. The embodiment shown in Fig. 1 is configured to set the irradiation angle [omega] by fixing the parallel beam X-ray irradiating device and rotating the specimen in uniaxial direction. The irradiation angle (ω) means the angle between the irradiated X-ray and the specimen. At this time, the detection device is located at an angle 2? (? =?) With respect to the irradiated X-ray. This irradiation angle and the position of the detection device are referred to as 2? (Theta) -ω (omega) method.

The 2θ-ω method is a method of fixing the parallel beam X-ray irradiator and moving the detector according to the uniaxial rotation angle of the specimen, a method of moving the parallel beam X-ray irradiator according to the uniaxial rotation angle of the specimen, Method and the like.

For example, after the X-ray irradiation angle (?) Is made a very small angle, the detection device can be rotated at a 2? Angle with reference to the X-ray to be irradiated. This method is a GI (Grazing incident) method, and the GI-SAXS method is also applicable. In the case of specimens coated with graphene on a silicon substrate, the detection device was fixed at a position where the peak of the graphene (hkl) crystal plane (mainly the (002) peak) and the X-ray irradiation angle ω).

In addition, the specimen can be angularly set by three-axis rotation (ψ (psi) and Φ (pi) in [Fig. 1]). According to the setting of the three-axis rotation angle of the specimen, it is possible to secure the x-ray irradiation angle and the detector angle with respect to the partial space at the upper part of the specimen. Thus, the diffracted X-rays existing in the upper portion of the specimen can be partially detected.

Ultrathin ultra-thin graphene In this case, a substrate without a substrate can be applied. In other words, it is possible to apply the removed graphene specimen by using the etching technique. In this case, the specimen may be damaged. In this case, the problem can be solved by moving the specimen in a limited manner and maximizing the degree of freedom of the angle with respect to the X-ray irradiation angle and the position of the detection device. By configuring the parallel beam X-ray irradiating device to rotate in the longitudinal and transverse directions by centrifugal rotation, it is possible to provide X-rays for all the spatial coordinates of the specific space.

In the present invention, a three-dimensional crystal structure or a specific crystal plane (for example, (002) plane) of the ultra-thin plate graphene specimen in which X-ray irradiation angle, specimen arrangement (angle) This is because it is necessary to overcome limitations of existing device technologies in order to analyze the difference in the upper and lower crystal planes in the three-dimensional peak shape or the symmetric crystal structure.

Specifically, in the case of a specimen in which a graphene film is formed or arranged on an X-ray non-transmissive substrate, the position of the X-ray diffracted according to the X-ray irradiation angle is all located in the semisphere of the upper portion of the specimen as shown in FIG. (Except for the lower hemisphere of the specimen). Therefore, the specimen is rotated on three axes (x, y, z), and when the parallel beam X-ray irradiating apparatus and the detecting apparatus are capable of centrifugal rotation in the longitudinal direction and the transverse direction, X-

As another example, in the case of a specimen having a graphene film formed or arranged on an X-ray transmissive substrate, or when the substrate is etched to make a free standing specimen only of the graphene film, the position of the transmitted X-ray or diffracted X- And can be located in the semisphere below the specimen as shown in Fig. Even in this case, the specimen is rotated on three axes (x, y, z), and when the parallel beam X-ray irradiator and detector can rotate centrally in the longitudinal and transverse directions, X- .

On the other hand, when a graphene film is formed or arranged on the X-ray transflective substrate, a part of the X-ray is transmitted and a part of the X-ray is reflected (diffracted) So that the diffracted X-rays can be placed on the spheres. Even in this case, the specimen is rotated on three axes (x, y, z), and when the parallel beam X-ray irradiator and detector can rotate centrally in the longitudinal and transverse directions, X- .

XRD  How to measure

The X-ray analysis method of the present invention described above is summarized as follows.

(1) X-ray irradiation apparatus: Parallel beam X-ray optics

(2) Detector: Array-type detector

(3) Measurement method: 2theta-omega mode, rocking curve measurement method, incidence angle fixing method, GI SAXS, 2D GISAXS method

(4) Graphene specimen: number of graphene layers 1 to 10 layers (thickness: 3 nm or less), size 0.3 × 0.3 cm or more

(5) In order to investigate the degree of deterioration of the ultimate thin film, a heat treatment device and a humidifying device were separately compared and analyzed.

(6) The specimen is configured to rotate in three axes (x, y, z axis), and the parallel beam X-ray irradiator and detector can be rotated in both longitudinal and lateral directions.

(002) Peak fitting method

Peak fitting of multi-layered film graphene (002) peaks was performed using a Gaussian function (G function) and a Lorentzian function (L function). In the present invention, Respectively. However, in addition to these G functions and L function fittings, if there are functions or programs that can satisfy the X-ray diffraction peaks, they may be used. Fundamentally, the FWHM and the peak center of the XRD peak of the same sample are constant eigenvalues irrespective of the time, place, and XRD device, and some errors may occur due to noise level, peak fitting function, and the like.

Example

9 is a graph showing XRD measurement data for S1 to S10. This measurement data does not mean the corresponding number of layers of S1 to S10. X-ray diffraction (XRD) spectra were prepared by mixing Cu Kα1 (1.540598 Å) and Kα2 (1.544426) at an intensity ratio of 2: 1. The 2θ was 20-50 ° and the step size was 0.016 °. 2theta ) -ω (omega) method. Parallel beam X-ray optics illuminator and array type detector were attached to X-ray diffraction equipment separately. A parallel beam X-ray mirror optics is used as a specific example of the parallel beam X-ray optics.

9 (a) is a graph comparing two samples of S1 and S2. The graphs are almost identical, and no peak shape was found except for the background scattering intensity. The fact that no peaks were observed even though the measurement was performed for a sufficiently long period of time for 30 to 50 minutes in one measurement shows that (002) peaks do not form like graphite (3-layer basic crystal structure).

(002) peaks start to appear slightly from (b) to [Fig. 10] (i) in FIG. 10, and the intensity tends to increase gradually. It can be seen that the precise number of layers of samples S3 to S10 is unknown but forms graphene crystals that are increasingly thick (ie, the number of layers increases). This is the crystallographic information on the thinnest thin film obtained first through the present invention.

The (002) peak information for the samples S3 to S10 is shown in detail in the table of FIG. For peak fitting, the baseline was set to S2. The G function and the L function are used as the peak fitting function, and these are separately shown in FIG.

Important information that can be obtained from the (002) peak is as follows.

(1) FWHM directly associated with graphene thickness

(2) d ₀₀₂ (obtained from the peak center 2?

(3) Grain thickness {D ₁ = d ₀₀₂ × (N _L -1) or D ₂ = d ₀₀₂ × (N _L )}, where N _L is the number of graphene layers

FIG. 10 shows the FWHM values for the samples S3 to S10 using the G function and the L function, the d ₀₀₂ values obtained from the 2θ values at the peak centers, and 2θ.

Importantly, the FWHM data relating to the graphene thickness, ie, the number of graphene layers, are independent from S3 → S4 → S5 and are decreasing with certain rules.

The FWHM value of the S6 sample is almost the same as that of the S5 sample. The FWHM values of the S7, S8 and S9 samples also have almost the same values, and the S10 sample has the smallest FWHM value independently. This information is very important.

The reason for this is that graphene crystals, like graphite, are found to have only a small amount of the initial (002) peak (FWHM: 4.663-5.06 °) in the S3 sample (S1 and S2 are observed) Information, and the thinnest graphene crystal layer (minimum number of layers) that can be measured by XRD like graphite crystal is three layers.

The S4 sample has relatively stronger intensity than the S3 sample, and the FWHM is independent and sharp (FWHM: 3.207-3.310 °) peak, which is certainly information about the four-layer graphene layer. ).

In addition, the S5 sample is very strong and very sharp (FWHM: 1.798-1.84 °) peak, which is very different from the S4 sample, which is certainly information about graphene where the main crystal is 5 layers (6 layers are not possible in the laminating process) .

The fact that the FWHM value of the S6 sample closely coincides with the value of the S5 sample FWHM reflects that the stacking process of S6 is only effective at about S5, i.e., the S6 sample shows information about the five-layer graphene crystal.

The S7 to S9 samples have similar values, and the FWHM is smaller with a tendency similar to that of the theoretical model, independent of the 5th layer graphene, which reflects the 6th layer graphene.

Finally, the S10 sample shows the strongest peak intensity and peak intensity, which is one step smaller than that of the six-layer graphene, which is information on the graphene seven-layer.

On the other hand, the graphene determinations of the number of layers for the samples S1 to S10 were determined from the XRD measurement on the rightmost side of the table (FIG. 10).

[Figure 11] is a table summarizing the usable values in the x-axis for drawing a calibration curve. When the absolute values of FWHM (°) of the number of graphene layers evaluated in FIG. 10 are taken as the y axis, the x axis can be the number of graphene layers (N _L ), and the graphene thickness (D) (1 / D). The graphene thickness (D) may be obtained by the analyte graphene film thickness (D ₁₎ and a maximum outer diameter between the analysis based on the distance the target graphene film thickness (D ₂₎ of the atoms relative to the inter-atomic center distance have.

D ₁ = d ₀₀₂ × (N _L -1) (where N _L is the number of graphene layers)

D ₂ = d ₀₀₂ x (N _L ) (where N _L is the number of graphene layers)

The calibration curve graphs for these are shown in (a), (b) and (c) of FIG. 12, respectively.

The red line (red circled dotted, denoted by Δ) reflects the result of the L function fitting and the blue line (blue triangle dotted, marked with ○) reflects the G function fitting results.

Various other types of calibration curves are possible. Even if the gap between the graphene layers d ₀₀₂ is the same, it may vary slightly depending on the laminating process. Even if the d ₀₀₂ value of the graphite is used as a fixed value, there is no big problem within the error range (See FIG. 13).

(D) of FIG. 12 is a graph comparing the data obtained by taking the x-axis as 1 / D and the y-axis as FWHM (the graph corresponding to (c) in FIG. 12) and the graph theoretically obtained by the sherrer equation Data. The theoretical sherrer equation becomes a complete linear graph toward the origin as the crystal size increases. On the other hand, in the case of experimental values, the tendency to deviate from the straight line when the number of graphene layers is 3 or 4 is very important data showing that the graphenes of the third and fourth layers, which are two-dimensional crystals, have properties different from general crystals.

In the case of graphene layers 5, 6 and 7, linear behavior toward the origin is shown as a theoretical value. This is also a very important result when the thickness of the unknown graphene specimen is near or greater than 13 Å (5 stories) The graphene thickness can be obtained.

[12] the dotted line shown in (d) of the So as a result of the linear fit for the pin 5 to 7 layers, in the case of a function of a straight line _{D 1 y = 22.358x + 0.220 (} G function fitting) and y = 22.141x +0.191 (L function fitting). For D ₂ , y = 32.743x + 0.062 (G function fitting) and y = 32.427x + 0.089 (L function fitting), where y is FWHM (°) and x is 1 / D. Degree (°) values of the FWHM in the y-axis can be appropriately modified by radians.

In addition to the graphene thickness or number of layers, the sizes of the nanofilms and nanocrystals can be found within the range of the slope including the error range of these calibration curves (see FIGS. 10 and 11) and the y intercepts obtained at this time. That is, when a straight line is drawn on the basis of the graphene layers 5, 6, and 7, the slope is about 14 to 40 in the error range, and the y intercept is in the range of -2 to 2. If a calibration curve is drawn after defining the error range based on the number of layers 3, 4, and 5, it has a slope and a slice which are quite different from the above values.

Therefore, in order to determine the error range of the graph and the calibration curve of FIG. 12 in the present invention, an important point is to determine the error of FWHM by the number of graphene layers. In the present invention, the FWHM errors of the samples S 3 to S 7 are set to ± 1.5 °, 1.0 °, 0.5 °, 0.4 ° and 0.4 °, respectively, from the measurement and fitting results of the additional samples. The maximum possible values were 14-30 slopes and -2-2 slopes.

Further, in Fig. 13, the slope and the slice of the maximum possible region were obtained under the assumption that the entire graphene layers 3 to 7 were straight lines. To do this, we define a Plot 2 (y = 12.6x + 1.1) straight line with a maximum slope Plot 1 (y = 82x-4.6) and a minimum slope, Area. At this time, the slope has 12 ~ 82 area and the y section has 1.12 ~ -4.6 area.

Although the range of the calibration curve is specified within the various error ranges, this study shows the absolute FWHM by the number of graphene layers in [Fig. 12]. When these are used as comparison data and unknown graphene is measured, the number of graphene layers can be determined by comparing and analyzing these data. For example, when the value of FWHM with respect to the XRD (002) peak obtained after the growth of the multilayered filmgraffin crystal is 2.5 °, the value of the present invention is 4 layers (3.207 °) and 1.8 layers ˚), which means that it is 4.5-layered. In reality, there is no graphene crystal called the 4.5-layer, but it gives very important information that the average value of the crystals in which there are several layers is 4.5 layers. To date, no such analysis has been provided.

If there is a program that is well suited to XRD peak analysis, the distribution of the number of graphene layers can be determined after evaluating the half-value width of the peaks after separating the peaks from the (002) peak fitting (compared with the present invention). For example, it is possible to separate the multiple peaks from each other without performing a single peak fitting on the sample, to provide information on the number of layers for each FWHM, to derive a crystal amount for each layer as a fitting peak area, 30% for the third floor, 40% for the fourth floor, and 30% for the fifth floor. What can be done in this way is another effect of the present invention.

XRD measurements were performed under conditions similar to or better than this test, which means that if the (002) peak is not observed, the number of graphene layers is one or two.

The rotation angle of the parallel beam X-ray source, detector, and specimen of the present invention can be rotated in the x, y, and z axes. All of these rotations are possible with current technology, but it is a technique that must be supplemented when analyzing extreme thin films.

[Example 5]

A variety of comparative experiments were performed for the sensitive samples S3 to S5. The experimental results are shown in [Table 1].

The information on the third to seventh layers in [FIG. 9] is a graph when (1) a parallel beam X-ray irradiator and (2) an array type detector operate simultaneously on the X-ray diffraction apparatus. (002) peak intensities of the S3 to S5 sensitive samples were set at 100, and were compared while changing the device description and measuring conditions. As shown in [Table 1], it can be seen that when the measurement temperature is in the range of 5 to 55 ° C (278 to 328 ° K) in the above two device technologies, there is almost no change in the peak intensity even for the sensitive graphene The range of 5 ~ 8 ℃ and the range of 45 ~ 50 ℃ is about 2%. In the case of rigorous experiment, the range of 8 ~ 45 ℃ is preferable. ).

However, when the temperature of the specimen is below 5 ° C or above 55 ° C, the peak disappears or sharply decreases, which is very important data showing that ultra-thin graphene can change during long-term measurement. Even at room temperature, the (002) peak of ultra-thin graphene disappears or sharply decreases when the humidity exceeds 70%. Such temperature changes (such as flicker, cloudy weather) and humidity range are common conditions that can occur in conventional X-ray diffraction experiments. If the (002) peak is not obtained or becomes very weak, it is possible to make a false interpretation. This phenomenon does not occur in conventional specimens and is the first phenomenon to be found in very thin graphene.

In Table 1, we compared the focused beam X-ray irradiator and the normal type detector, which are widely analyzed in general nano thin films. When using the focused beam X-ray irradiator, . This is interpreted to be due to the fact that the x-ray with good permeability is focused (focused) and is mostly transmitted through the graphene membrane. This phenomenon does not occur in the conventional nano thin film analysis and is the first phenomenon to be found in very thin graphene.

Also, when the detector is normal to the paralbeam X-ray irradiator, the peak does not come out or weakens (see [Table 1]).

Therefore, in the present invention, when the number of layers of graphene ultrathin films is 1 to 10 layers, it is necessary to use a parallel beam X-ray beam, and the Array type detector functions to increase the reliability of measurement. Also, the temperature should be 5 ~ 45 ℃ (278 ~ 328 ℃) and the humidity should be less than 70% as the measurement condition, even if the condition of the measuring device is good.

Changes in the extreme graphene film at temperatures below 5 ° C and above 55 ° C and above 70% humidity can be explained by very weak van der Waals bond strength between graphene layers. The adsorption of H ₂ O water molecules is usually strong so that the water around graphene adsorbs to the graphene surface and some water molecules permeate between weak graphene layers to weaken the crystallinity of graphene, It can be interpreted that the crystallinity is weakened by affecting the cohesiveness (volume increase) and molecular unit vibration of these adsorbed water.

[Example 7]

In the case of S7 in FIG. 9, two methods are possible when the parallel beam X-ray is irradiated to the graphene sample and the measurement method for detecting the X-ray diffracted by the detector is ω (omega) -2theta (theta). That is, the incident angle is fixed and the incident angle is rotated. In the present invention, it is understood that some of the crystal planes of the silicon wafer cause some interference with the graphene (002) peak. It was not easy to observe the graphene (002) peak due to the relatively high intensity of the silicon wafer peak when the 4-layer graphene sample was separately measured with a general ω (omega) -2theta (theta). In order to solve this problem, the parallel beam X-ray irradiation angle was fixed at the derived angle according to the following [illumination angle derivation formula]. Thus, the silicon peak was not emitted and only the graphene (002) peak could be obtained.

[Investigation angle derivation expression]

X-ray irradiation angle = (2? _{( Hkl )} 2) 占 1 占

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

[Example 8]

[Fig. 13] is a graph (2? = 42.525 °) showing a peak for another (hkl) crystal plane which is not the (002) peak of the graphene number 7 found using the GI SAXS method. This peak can not be found in the usual way. This is because it is not a crystal plane provided on the vertical plane of the thin film. In addition to the crystal vertical plane, there are various peaks on the xy plane of the crystal horizontal plane, and the GI SAXS method is required to find them. In the present invention, a peak other than the (002) crystal face of the seventh layer graphene was found by using this method. Although the hkl index has not yet been determined, the principle of the present invention can be applied to this peak as it is (see d _{( hkl )} and FWHM theory). We will also look for another (hkl) decision through the GI SAXS law, but it takes too long. However, using GI SAXS with 2D GI SAXS, that is, a 2D GI SAXS device, it is possible to find peaks of the graphene xy crystal plane in a short time, and to find the graphene layer number determination information (defect constants) You can get accurate information.

The GI SAXS method is powerful enough to find another peak that is much less intense than the graphene (002) peak. Therefore, in the present invention, the GI SAXS method can also be used for finding the (002) plane of graphene. Further, 2D GISAXS with a 2D detector can more easily detect graphene peaks. The principle of the present invention can be applied to a 3-dimensional (or 2.5-dimensional: partial spatial cover) detector concept to be developed in the future.

[Fig. 14] is a graph of a rocking curve with respect to graphene crystal planes of 3 to 10 layers (S3 to S10). The x-axis is the angle of the omega (°). This rocking curve is a very important measure of how much the (hkl) crystal plane is tilting (tilting, etc.) and how tilted it is. When measuring the rocking curve, the angle of the detector was fixed to the angle derived from the following [Detection angle derivation formula]. After this, the x-ray diffraction intensity was measured while the omega angle was minutely varied from + to -.

[Detection angle derivation expression]

Detector irradiation angle = (2? _{( Hkl )} ) 占 占

2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

The rocking curve with respect to the graphene (002) crystal face is shown in Fig. [Fig. 14] The center value of the peak is 1/2 of the peak 2? Of the graphene (002) crystal plane shown in Fig. 9. 10 layer Grading (S10) Rocking curve When the peak center line of the graph is taken as a reference, the crystal orientation center and distribution of each layer graphene crystal are different (peaks in [Fig. 14] are crystal orientation distribution functions ), The intensity decreases from the center to the edge, indicating the degree of tilt of the crystal plane located at a plane (0 °) where the center of the peak coincides with the xy axis of the crystal. That is, when the x-axis of [Fig. 14] is redrawn, the peak center is 0 °, the left side is an angle tilted to a minus angle, and the right side is an angle tilted to a positive angle. Represents the distribution function of graphene (002) crystal planes existing at an angle. Accordingly, the present invention also provides the first XRD information showing that the two-dimensional graphenes by layer number exist in a form (+, 0, - distribution) rather than a perfect two-dimensional plane.

[Example 9]

A vacuum thermal processing system and a cooling system, such as liquid nitrogen, can be placed in the extreme analytical thin film device to maximize the adverse effects at temperatures below 5 ° C and above 55 ° C and above 70% humidity. As shown in [Table 2], in the case of 6-layer graphene, it is possible to observe the change behavior of d ₀₀₂ graphene spacing in vacuum heat treatment. As the temperature increases, the interplanar spacing decreases and becomes larger, which can be interpreted as an increase in crystal quality due to the annealing effect and an increase in interplanar spacing due to molecular vibration at higher temperatures. [Table 2] can also study the interplanar spacing of extreme graphene thin films even in the cooling test using liquid nitrogen. In this case, the interplanar spacing can be explained by the reduction of thermal vibration energy of graphene molecules, association of absorbed water molecules, and solid phase change.

[Example 10]

FIGS. 10 to 12 show the FWHM of the number of graphene layers, which can be used as a reference to evaluate the number of unknown graphene layers. This principle is a technique that has not existed in existing extreme thin films. For example, when the value of FWHM for the XRD (002) peak obtained after the growth of the multilayered filmgraffin crystal is 2.5 °, the value of this graph is 4 layers of graphene (3.207 °) and 1.844 ˚), which means that it is 4.5-layered. Theoretically, there is no graphene crystal called the 4.5-layer, and it gives very important information that the average value of the crystals in which there are several layers is 4.5 layers. To date, no such analysis has been provided. This principle is equally applicable to the various grades mentioned in the introduction (kind, classification, doping, oxygen and sulfur components, surface modifiers, etc.).

[Example 11]

When the size of the S3 specimen of FIG. 9 (1 cm × 1 cm) was set to half (0.5 cm × 0.5 cm), the peaks completely disappeared. In the case of S5 specimen (1 cm x 1 cm), when the width and the size of the specimen were 0.3 cm x 0.3 cm, the peak disappeared completely. That is, it was found that the crystal peak of the ultimate thin film having the minimum thickness can be obtained only when the size of the specimen is 0.3 to 0.5 cm × 0.5 cm or more. The size of the specimen is preferably as large as possible, but the preferred size of the specimen in the present invention is preferably at least 0.5 cm x 0.5 cm (the larger the number of graphene layers, the smaller the size of the specimen).

[Example 12]

As a result of measuring the omega-2 theta mode used in the S3 specimen measurement of FIG. 10 by the Thrta-2Theta measurement method used in the general powder type XRD, the (002) peak was not observed. Therefore, the present invention shows that the ultimate thin film can obtain crystallographic information of the three-layer graphene only when various device options are combined and the environmental measurement conditions and the measurement method are combined at the same time.

[Example 13]

The CVD graphene used in the S10 specimen of FIG. 10 was transferred to a metal holder having a size of 8 mm × 8 mm (width × length) and then placed in the center of the X-ray analyzer, and the X- After irradiation to the lower right side, the irradiated X-rays were measured by omega-2theta after the graphene was placed and the substrate was empty and the FWHM of the (002) crystal face was obtained. The transmittance decrease due to absorption and scattering of graphene specimen itself was about 1 ~ 3.5. The FWHM of the (002) crystal was analyzed and compared with the graphene reference in the previous section, the number of layers was 5.8. Unlike conventional X-ray reflection, X-ray scattering, X-ray fluorescence, and X-ray diffraction, such experiments are performed by X-ray transmission analysis by transmission, X-ray absorption by transmission, and X-ray diffraction by transmission, It is possible.

[Example 14]

The Hummers method, the Brodie method, the Hofman & Frenzel method, the Hamdi method, the Staus method, and the like including the Modified Hummers method can be used as a method for producing the graphene oxide. The Modified Hummers method is used in the present invention. As a concrete example, 50 g of micro graphite powder and 40 g of NaNO ₃ are put into a 200 mL H ₂ SO ₄ solution, and 250 g of KMnO ₄ is slowly added over 1 hour while cooling. Then slowly add ₅ L of 4-7% H ₂ SO ₄ over 1 hour and add H ₂ O ₂ . Thereafter, the precipitate was centrifuged and washed with 3% H ₂ SO ₄ -0.5% H ₂ O ₂ and distilled water to obtain a yellowish brown graphene oxide water-based slurry. This was coated on PET to a thickness of 300 nm, dried at 150 ° C, and peeled. The peeled graphene membrane was placed on a metal holder having a size of 8 mm × 8 mm (width × length), and then fixed with a physical fixing method (covering the cover and screwed) Respectively. The transmittance decrease due to absorption and scattering of graphene specimen itself was about 20 ~ 25. (002) crystal plane was observed near 2? = 12 degrees.

The hot wire was also irradiated by an IR lamp near the holder so that the graphene specimen could be locally heat treated. After 10 minutes, the temperature reached near 400 ° C, indicating that the decrease in x-ray transmittance (or increase in absorption rate) was increased to 10-15. It also shows that there is a very large change in 2θ = around 22 degrees. It is interpreted that the graphene oxide is thermally reduced to graphene, so that the thickness becomes thinner (transmittance decreases) and the interlayer spacing becomes narrower. Investigation of the FWHM of the thermally reduced graphene (002) crystal plane revealed that the number of layers was about 6.4. It can be seen that the number of layers of graphene contained in the graphene powder or graphene dispersion is 1 to 10 layers, and the principle of the present invention is applied, and only the thickness of the sample shows that these graphenes are simply stacked. Therefore, the present invention means that the number of layers is 1 to 10 in the case of CVD graphene and 1 to 10 in the case of graphene powder. Unlike the conventional X-ray reflection method, X-ray scattering method, X-ray fluorescence method, and X-ray diffraction method, graphene powder or graphene oxides are used for X-ray transmission analysis by transmission, X-ray absorption method by transmission, X- Shows that diffraction is possible in extreme thin film graphenes.

[Example 15]

In detail, the chemical reduction method is as follows: 1 g of hydrazine hydrate is added to 2 g of 3% graphene oxide slurry and 100 ml of distilled water is well dispersed. Then, 1 ml of hydrazine hydrate is added and the mixture is reduced at 100 ° C. for 3-24 hours. It is filtered with filter paper and washed with water and methanol. A process may be used in which a salt of an alkali metal or an alkaline earth metal such as KI or NaCl is treated to remove H ₂ O beforehand from graphene oxide to partially restore the carbon-carbon double bond before treating a strong reducing agent such as high- . As a specific experimental example, 6 g of KI is added to 5% graphene oxide slurry and left for 6 days to complete the reaction. It is then rinsed with distilled water and filtered. In addition to the hydrazine method and the KI method, there are NaBH ₄ , Pyrogallol, HI, KOH, Lawesson's reagnet, Vitamin C, Ascorbic acid and the like as a method of introducing a reducing agent into other graphene oxide aqueous solution. Analysis of the (002) crystal planes of the graphene produced by reflection and transmission diffraction revealed that the number of layers was 4.8 and 4.7 (FWHM of (002) crystal face), respectively, which is a relatively accurate figure within the error range. In the case of X-ray transmittance, only the transmission type specimen was available in this experiment. In order to be able to analyze various extreme thin films by using the transmission type and reflection type X-ray, the X-ray irradiator, the detector and the specimen should be able to move in the x, y and z axes in the three-dimensional sphere. This makes it possible to analyze other hidden crystal planes, and to analyze low angle transmission and low angle absorption methods, and to compare mutual comparison of low angle reflection methods (scattering methods) (surface roughness, X-ray absorption, fluorescence analysis, etc.) need).

Although the present invention has been described by way of examples only with respect to the X-ray transmission, X-ray absorption, x-ray diffraction by reflection, x-ray diffraction by transmission, diffraction of a specific x-ray crystal plane, Such as x-ray diffraction, x-ray reflection, x-ray transmission, x-ray absorption, x-ray scattering, x-ray fluorescence, and x-ray imaging.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It is therefore intended that the appended claims cover such modifications and variations as fall within the true scope of the invention.

none

Claims (6)

(a) a chamber controlled to a temperature condition of 278 to 328 ° K and a humidity condition of less than 70%, a chamber in which a specimen is placed, a parallel beam X-ray irradiator for irradiating the specimen in the chamber with X- Preparing an X-ray analyzing apparatus configured by including a detecting device for detecting a line;
(b) removing a part or all of the substrate in a state where a graphene film of 1 to 10 layers is bonded to a substrate having a size of 0.3 x 0.3 cm or more in the chamber, and a graphene specimen configured to transmit X- Placing on a specimen table configured to not affect the transmission of the line;
(c) irradiating X-rays to the graphene specimen with the parallel beam X-ray irradiator to detect and analyze X-rays transmitted through the detector; Gt; X-ray < / RTI > transmission assay for graphene having a very fine thickness.
The method of claim 1,
The graphene specimen includes a specimen (hereinafter, referred to as an A type specimen), a specimen from which a substrate is partially removed (hereinafter, referred to as a B type specimen), a B type specimen (Hereinafter referred to as a 'C type specimen') transferred to a porous substrate and a specimen prepared by etching a transfer substrate of the C type specimen (hereinafter referred to as 'D type specimen') Gt; X-ray < / RTI > transmission assay for graphene having a very fine thickness.
The method of claim 1,
Wherein the graphene specimen is prepared by physically placing a graphene film prepared in advance on a substrate from which a part of the plate surface has been removed.
The method of claim 1,
The step (a) may include preparing a second detecting device for detecting X-rays reflected by the graphene specimen,
Wherein the step (c) comprises setting the X-ray irradiation angle in the parallel beam X-ray irradiating device and the arrangement of the second detecting device by a 2? (?) -? (Omega) method. X-ray transmission assay method for graphene.
5. The method of claim 4,
Wherein the step (c) comprises setting an angle of an X-ray irradiated on the graphene specimen within a range derived from the following [irradiation angle derivation formula]. Way.
[Investigation angle derivation expression]
X-ray irradiation angle = (2? _{( Hkl )} 2) 占 1 占
2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index
5. The method of claim 4,
Wherein the step (c) includes setting the second detecting device on the basis of the graphene specimen within an angle range derived from the following [detection angle derivation formula]: X Ray transmission analysis method.
[Detection angle derivation expression]
X-ray detection angle = (2? _{( Hkl )} ? 2) 占 1
2 &thetas; (hkl): Diffraction angle of the peak center of the reference graphene crystal plane having a specific Miller index

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