KR20210156357A - Germanium-Phosphide Nanosheets and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to a germanium phosphide nanosheet for an optoelectronic device having a bandgap in a visible-near-infrared region, and a preparation method thereof. As the germanium phosphide nanosheet of the present invention has a band gap in the visible-near-infrared region, the germanium phosphide nanosheet is sufficient to efficiently collect visible-near-infrared light and suitable for water decomposition using sunlight. The band gap is greatly increased due to quantum confinement effect, so the germanium phosphide nanosheet can be used as a conductive semiconductor material. In addition, the germanium phosphide nanosheet of the present invention is a pure crystalline phase without impurities by not using a catalyst, and can be prepared as a low-cost process at the relatively low temperature.

Description

Germanium-Phosphide Nanosheets and Preparation Method Thereof

The present invention relates to a germanium-phosphide nanosheet for an optoelectronic device having a bandgap in the visible-near-infrared region, and a method for manufacturing the same.

In general, solids are classified into 0-dimensional (0D), 1-dimensional (1D), 2-dimensional (2D), and 3-dimensional (3D) depending on the crystal structure. As the characteristics change, physical properties such as mechanical strength and electrical conductivity change. When the shape of a material is reduced from a bulk crystal to two dimensions, a quantum confinement effect appears and the band gap increases or electrical properties change significantly.

Among them, graphene is a representative material with a two-dimensional structure composed of one layer of carbon atoms, has excellent strength against mechanical bending and stretching, is harder than diamond, and has high carrier mobility (10 ⁵ cm ² / Vs) has In addition, the graphene (graphene) has a characteristic of transmitting most of the incident light, it is used as a material for a transparent electrode, and shows a characteristic similar to that of a metalloid having a cone-shaped band gap. Therefore, although research for application to flexible solar cells and flexible displays is being conducted, there is a problem in that it is not easy to apply to devices such as field effect transistors (FETs) because there is no band gap in reality.

In order to solve this problem, many studies are being conducted to find a new two-dimensional material, such as graphene, in which atomic layers are accumulated by van der Waals forces.

Recently, transition metal dichalcogenides (TMD) compounds having a two-dimensional structure include MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , and the like, which are attracting much attention due to their large bandgap energy. The transition metal dichalcogen (TMD) compound monolayer has a much larger bandgap energy than a three-dimensional crystal. That is, the three-dimensional crystal of the transition metal dichalcogen (TMD) compound has a band gap of 1.1 eV, whereas the monolayer of the transition metal dichalcogen (TMD) compound is 1.9 eV, which is 0.8 eV larger.

In addition, since the transition metal dichalcogen (TMD) compound monolayer has a bandgap structure in which light absorption and light emission characteristics are greatly increased, it is attracting attention as an excellent light emitting material emitting a red wavelength.

In addition, black phosphorus or phosphorene, which consists of a single element of group V having a two-dimensional structure, is also receiving a lot of attention. When the black phosphorus or phosphorene becomes a monolayer, the bandgap energy value increases from 0.35 eV to 1.7 eV, and the carrier mobility increases to 10 ⁴ cm ² /Vs, so it is expected as an excellent conductive material. are collecting However, the black phosphorus or phosphorene monolayer has a weak problem in moisture, oxygen, and heat, and a complementary method is being developed.

If the weakness of the black phosphorus or phosphorene monolayer to moisture, oxygen, and heat is solved, it will provide a great opportunity to design a high-performance electronic device at a low price.

In addition, Group V As and Sb are also being developed as two-dimensional materials, and Group IV Si and Ge have also succeeded in synthesizing two-dimensional materials by chemical vapor deposition using a silver substrate as two-dimensional materials.

In addition, while compensating for the instability of the two-dimensional group V, a binary compound semiconductor in which groups IV and V are combined instead of group IV, which can be obtained by applying a difficult synthesis method, is attracting attention. That is, the binary compound semiconductor combining groups IV and V is stable to oxygen and moisture, and the band gap of the single layer of the binary compound semiconductor combining groups IV and V is the transition metal dichalcogen ( TMD) compound monolayer or black phosphorus or phosphorene (black phosphorus or phosphorene) has a higher characteristic than group V, so it is expected to complement the disadvantages of the existing two-dimensional material.

In addition, two-dimensional group IV-V MX compounds (M = Si, Ge, Sn and X = P, As, Sb, Bi) have been proposed from recent theoretical calculations. That is, SiP, SiAs, GeP, GeAs, SnP, etc. were predicted as a two-dimensional layered structure. According to the theoretical calculation, the bandgap of the three-dimensional crystal of the MX compound (M = Si, Ge, Sn and X = P, As, Sb, Bi) is less than 1 eV, whereas the MX compound (M = Si, Ge, Sn and When X = P, As, Sb, Bi) becomes a monolayer, the band gap rises in the range of 2 to 3 eV. Accordingly, it is predicted that it is sufficient to efficiently collect visible light and has a bandgap position suitable for water decomposition using sunlight. In addition, the MX compound (M = Si, Ge, Sn and X = P, As, Sb, Bi) monolayer is evaluated as an excellent conductive semiconductor material in which the ^{carrier mobility increases up to 10 3} cm ^{2 /Vs.}

In addition, high-temperature melt growth method using a catalyst was used as a crystal growth method for materials containing group V among two-dimensional materials. At this time, as the reaction catalyst material, Bi, Pb, I ₂ and the like are mixed and synthesized. Accordingly, crystals synthesized using a catalyst have disadvantages in that the catalyst components remain as impurities and are doped or precipitated together as crystals, and thus a purification process is required and the properties of the synthesized crystals are deteriorated.

US Registered Patent Publication No. 10483355 US Patent Publication No. 2019-0221483 European Patent Publication No. 1878043 US Registered Patent Publication No. 9513436

The present invention provides a germanium phosphide nanosheet and a manufacturing method thereof, a germanium-phosphide nanosheet for an optoelectronic device having a bandgap in the visible-near-infrared region, and the germanium-phosphide nanosheet An object of the present invention is to provide a simple and economical manufacturing method capable of inexpensively producing a pure crystalline phase without impurities by not using a catalyst.

A germanium-phosphide nanosheet according to an embodiment of the present invention includes a germanium-phosphide nanosheet for an optoelectronic device having a band gap in the visible-near-infrared region.

The band gap of the germanium-phosphide nanosheet according to an embodiment of the present invention may be 0.92 eV to 2.5 eV.

In the germanium-phosphide nanosheet according to an embodiment of the present invention, a molar ratio of germanium (Ge) to phosphorus (P) may be 1:5 to 5:1.

In the germanium-phosphide nanosheet according to an embodiment of the present invention, germanium (Ge) and phosphorus (P) may be uniformly distributed in the nanosheet.

The crystalline phase of the germanium-phosphide nanosheet according to an embodiment of the present invention may be a monoclinic crystal system crystalline phase.

A space group of the germanium-phosphide nanosheet according to an embodiment of the present invention may be C2/m.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타날 수 있다.When XRD analysis of the germanium-phosphide nanosheet in the monoclinic crystal system crystal phase according to an embodiment of the present invention

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak may appear at 27.0° to 29.0°.

The lattice constant a of the Germanium-Phosphide nanosheet in the monoclinic crystal system crystal phase according to an embodiment of the present invention is 15.140 Å, the lattice constant b is 3.638 Å, and the lattice constant c is 9.190 Å , and the lattice constant β may be 101.1°.

The germanium-phosphide nanosheet according to an embodiment of the present invention may be a single crystal.

The germanium-phosphide nanosheet according to an embodiment of the present invention has a monolayer of a layered structure, and an interlayer distance of the monolayer may be 1 to 5 Å.

면간거리

은 6.4 Å 일 수 있다. _{(204) interplanar distance d 204} of the germanium-phosphide nanosheet according to an embodiment of the present invention is 2.1 Å,

face-to-face distance

may be 6.4 Å.

The thickness of the germanium-phosphide nanosheet according to an embodiment of the present invention may be 0.8 nm to 200 nm.

Germanium-Phosphide (Germanium-Phosphide) nanosheet manufacturing method according to an embodiment of the present invention

preparing a reactant by mixing germanium (Ge) powder and phosphorus (P) powder in a molar ratio (Ge:P) of 1:5 to 5:1;

putting the reactant in a quartz ampoule and sealing in a vacuum state;

Putting a quartz ampoule containing the reactant in a temperature-controlled electric furnace and synthesizing it by melting it at a high temperature for a reaction temperature of 1000 to 1400° C. and a reaction time of 12 to 64 hours to grow crystals to obtain germanium phosphide crystals;

exfoliating the germanium phosphide nanosheets by placing the germanium phosphide crystals in an organic solvent and ultrasonicating them intermittently for 1 to 5 hours at a temperature of 2 to 10° C. using an ultrasonic device; and

and centrifuging the peeled solution to collect the liquid in the upper layer, and then evaporating the organic solvent of the liquid to obtain a germanium phosphide nanosheet powder.

The crystalline phase of the germanium-phosphide nanosheet according to an embodiment of the present invention may be a monoclinic crystal system crystalline phase.

Since the germanium phosphide nanosheet of the present invention has a band gap in the visible-near-infrared region, it is sufficient to efficiently collect visible light, and is suitable for water decomposition using sunlight.

In addition, the germanium phosphide nanosheet of the present invention can be used as a conductive semiconductor material because the band gap is greatly increased due to the quantum confinement effect.

In addition, the germanium phosphide nanosheet of the present invention does not have any change in physical properties even under high humidity conditions at room temperature or high temperature.

In addition, since the germanium phosphide nanosheet of the present invention is composed of only two components of germanium and phosphorus, it does not cause environmental pollution.

And, the method of manufacturing the germanium phosphide nanosheet of the present invention can be performed at a relatively low temperature and low-cost process.

1A is a schematic diagram of a melt growth method for synthesizing a germanium phosphide compound semiconductor crystal, which is a raw material of a germanium phosphide nanosheet according to an embodiment of the present invention, and FIG. 1B is a graph for the reaction conditions of the melt growth method.
2 is a photograph of a crystal mass of a germanium phosphide compound semiconductor synthesized by a melt growth method according to an embodiment of the present invention.
3 is a schematic image of a process of manufacturing a germanium phosphide nanosheet by exfoliating a germanium phosphide compound semiconductor crystal mass according to an embodiment of the present invention by a mechanical method.
4 is an X-ray diffraction (XRD, X-Ray Diffraction) pattern of a germanium phosphide crystal and a germanium phosphide nanosheet according to an embodiment of the present invention.
5A is an XRD diffraction pattern of a germanium phosphide-germanium mixed crystal according to a comparative example of the present invention, and FIG. 5B is an enlarged XRD diffraction pattern.
6A is a schematic image of the crystal structure of a germanium phosphide nanosheet calculated in a ball-and-stick model according to an embodiment of the present invention, and FIGS. 6B and 6C are images according to an embodiment of the present invention A scanning electron microscope (SEM) image of a germanium phosphide nanosheet, FIGS. 6i and 6ii are a transmission electron microscope (TEM) image of a germanium phosphide nanosheet according to an embodiment of the present invention, and FIG. 6d is an energy-dispersive X-ray spectroscopy (EDX) element mapping result and element content analysis result of a germanium phosphide nanosheet according to an embodiment of the present invention.
7 is a diffuse reflection spectrum in an absorption mode in which band gaps of a germanium phosphide crystal and a germanium phosphide nanosheet according to an embodiment of the present invention are measured.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and therefore, the scope of the present invention is not to be construed as being limited by these examples.

As used herein, an expression such as “comprising” is understood as an open-ended term that includes the possibility of including other embodiments, unless specifically stated otherwise in the phrase or sentence in which the expression is included. should be

As used herein, “preferred” and “preferably” refer to embodiments of the invention that may provide certain advantages under certain circumstances. However, other embodiments may also be desirable, under the same or other circumstances. Additionally, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

Hereinafter, the germanium phosphide (Germanium-Phosphide) nanosheet of the present invention will be described in detail.

The germanium-phosphide nanosheet of the present invention includes a germanium-phosphide nanosheet for an optoelectronic device having a band gap in the visible-near-infrared region.

Solids are classified into 0-dimensional (0D), 1-dimensional (1D), 2-dimensional (2D), and 3-dimensional (3D) according to their crystal structure. Therefore, physical properties such as mechanical strength and electrical conductivity are changed.

In particular, when the shape of a material is reduced from a bulk crystal to two dimensions, a quantum confinement effect appears and a band gap increases or electrical properties change significantly.

The germanium phosphide (Germanium-Phosphide) nanosheet may exhibit a band gap in the visible-near-infrared region.

The band gap of the germanium-phosphide nanosheet may be 0.92 eV to 2.5 eV.

The band gap of the germanium-phosphide nanosheet may be 500 nm to 1350 nm in terms of wavelength.

In addition, the band gap of the germanium phosphide (Germanium-Phosphide) nanosheet may be preferably 1.2 eV to 2.4 eV, more preferably 1.5 eV to 2.4 eV, even more preferably 1.7 eV to It can be 2.3 eV.

The germanium phosphide (Germanium-Phosphide) has a band gap of 0.5 to 0.9 eV when it is a bulk crystal, and a band of 0.92 to 2.5 eV when it becomes a nanosheet composed of multiple layers (multilayer including single layer, double layer, triple layer, etc.) A change in the gap can be induced.

Here, Germanium-Phosphide, a type of two-dimensional group IV-V MX compound (M = Si, Ge, Sn, and X = P, As, Sb, Bi), has multiple layers (single layer, double layer, triple layer). When the nanosheet is composed of multiple layers including layers, the bandgap rises. Accordingly, the germanium-phosphide nanosheet is sufficient to efficiently collect visible light and has a band gap suitable for water decomposition using sunlight. In addition, the germanium-phosphide (Germanium-Phosphide) nanosheet is an excellent conductive semiconductor material having a significantly increased band gap due to an increase in quantum confinement effect.

In the germanium-phosphide nanosheet, a molar ratio of germanium (Ge) to phosphorus (P) may be 1:5 to 5:1.

In addition, in the germanium-phosphide nanosheet, a molar ratio of germanium (Ge) to phosphorus (P) may be preferably 1:3 to 3:1, and more preferably 1:1.

When the molar ratio of germanium (Ge) and phosphorus (P) is included in the above range, the germanium-phosphide nanosheet has a band gap within visible-near-infrared rays due to the quantum confinement effect, so that visible-near-infrared rays are efficiently transmitted can be collected

In addition, when the molar ratio of germanium (Ge) to phosphorus (P) is not included within the above range, the germanium-phosphide nanosheet has a band gap outside the visible-near-infrared rays, so that the visible-near-infrared rays are efficiently collected. Can not.

Here, the germanium phosphide (Germanium-Phosphide) nanosheet is a molar ratio of germanium (Ge) and phosphorus (P) of 1:5 to 5:1 energy-dispersive X-ray spectroscopy (EDX) ) can be confirmed by spectral analysis.

And, in the germanium-phosphide nanosheet, germanium (Ge) and phosphorus (P) may be uniformly distributed in the nanosheet.

Here, the method for confirming that the germanium (Ge) and the phosphorus (P) are uniformly distributed on the germanium-phosphide nanosheet is energy-dispersive X-ray (EDX) The germanium (Ge) and phosphorus (P) mapping is performed by spectroscopy.

In the image obtained by mapping the germanium (Ge) and the phosphorus (P) by the energy-dispersive X-ray spectroscopy (EDX), the germanium (Ge) and the phosphorus (P) elements are the phosphorus It is evenly distributed in the Germanium-Phosphide nanosheet.

In addition, the crystalline phase of the germanium-phosphide nanosheet may be a monoclinic crystal system crystalline phase.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타날 수 있다.Here, when XRD analysis of the germanium-phosphide nanosheet in the monoclinic crystal system

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak may appear at 27.0° to 29.0°.

A space group of the germanium-phosphide nanosheet may be C2/m.

And, the lattice constant a of the Germanium-Phosphide nanosheet of the monoclinic crystal system crystal phase is 15.140 Å, the lattice constant b is 3.638 Å, the lattice constant c is 9.190 Å, and the lattice constant β may be 101.1°.

In addition, the germanium phosphide (Germanium-Phosphide) nanosheet may be a single crystal (single crystal).

Here, when the germanium-phosphide nanosheet is a single crystal, the electron beam is diffracted by a single crystal in a Fast Fourier Transform (FFT) image of a transmission electron microscope (TEM) and a Selected Area Electron Diffraction (SAED) pattern. It can be confirmed from what appears to be separated into dots.

And, the germanium-phosphide (Germanium-Phosphide) nanosheet has a monomolecular layer having a layered structure, and the interlayer distance of the monomolecular layer may be 1 to 5 Å.

In addition, the germanium-phosphide (Germanium-Phosphide) nanosheet has a monomolecular layer having a layered structure, and the interlayer distance of the monomolecular layer may be preferably 1 to 4 Å, more preferably 1 to 3 Å.

면간거리

은 6.4 Å 일 수 있다.And, the (204) interplanar distance d ₂₀₄ of the germanium phosphide (Germanium-Phosphide) nanosheet is 2.1 Å,

face-to-face distance

may be 6.4 Å.

In addition, the germanium-phosphide (Germanium-Phosphide) nanosheet may have a thickness of 0.8 nm to 200 nm. Here, the germanium phosphide nanosheet is uniformly formed so that the thickness of the germanium phosphide nanosheet can be increased from a few Å to a bulk size of several hundreds of μm.

In addition, the thickness of the germanium phosphide (Germanium-Phosphide) nanosheet may be preferably 0.8 nm to 150 nm, more preferably 1 nm to 100 nm, even more preferably 1 nm to 50 nm can be

Hereinafter, the germanium-phosphide (Germanium-Phosphide) nanosheet manufacturing method of the present invention will be described in detail.

The germanium phosphide (Germanium-Phosphide) nanosheet manufacturing method of the present invention is

preparing a reactant by mixing germanium (Ge) powder and phosphorus (P) powder in a molar ratio (Ge:P) of 1:5 to 5:1;

putting the reactant in a quartz ampoule and sealing in a vacuum state;

Putting a quartz ampoule containing the reactant in a temperature-controlled electric furnace and synthesizing it by melting it at a high temperature for a reaction temperature of 1000 to 1400° C. and a reaction time of 12 to 64 hours to grow crystals to obtain germanium phosphide crystals;

exfoliating the germanium phosphide nanosheets by placing the germanium phosphide crystals in an organic solvent and ultrasonicating them intermittently for 1 to 5 hours at a temperature of 2 to 10° C. using an ultrasonic device; and

and centrifuging the peeled solution to collect the liquid in the upper layer, and then evaporating the organic solvent of the liquid to obtain a germanium phosphide nanosheet powder.

As an embodiment, as a process of manufacturing a germanium phosphide nanosheet by exfoliating a germanium phosphide compound semiconductor crystal mass by a mechanical method, a bulk crystal, which is a crystal mass of the germanium phosphide compound semiconductor synthesized by a melt growth method, is prepared by mortar Or, grind it to pulverize it into small crystals using a pulverizing device such as a ball mill.

The germanium phosphide crystals pulverized into the small crystals are added to an organic solvent to prepare a solution in which the germanium phosphide crystals are dispersed. Then, the reactor containing the dispersion solution is sonicated in a general ultrasonicator (Hwashin 605, 40 kHz, 350 W) for 1 to 3 hours. It is then placed in a high-density probe ultrasonicator (Sonics VCX-130; 20 kHz, a maximum power output of 130 W) operating at 20% amplitude. The reactor containing the solution is placed in a water jacket connected to a circulator with a temperature controller, and the reactor temperature is maintained at 2 to 10 °C. The ultrasonic tip of the high-density probe ultrasonicator exfoliates the germanium phosphide crystal using the high-density probe ultrasonicator for 1 to 3 hours in such a way that it reacts for 10 seconds and has a break for 2 seconds to prevent excessive heating. After the exfoliation, the supernatant liquid containing the exfoliated germanium phosphide nanosheets is collected by centrifugation at 3000 to 15000 rpm for 10 minutes to 1 hour. After evaporating the organic solvent from the upper liquid, germanium phosphide nanosheets are obtained in powder form.

Here, when synthesizing the germanium phosphide crystal, materials other than the germanium (Ge) powder and the phosphorus (P) powder are not used.

In addition, when synthesizing the germanium phosphide crystal, a reaction catalyst such as _{Bi, Pb, or I 2 is not used.}

Therefore, after synthesizing the germanium phosphide crystal, the catalyst component remains as an impurity and is not doped or precipitated as crystals, and a purification process is not required for them. The physical properties of the germanium crystal are not deteriorated either.

The crystal phase of the germanium-phosphide crystal may be a monoclinic crystal system crystal phase.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타날 수 있다.In addition, when XRD analysis of the germanium phosphide (Germanium-Phosphide) crystal

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak may appear at 27.0° to 29.0°.

The lattice constant a of the germanium-phosphide crystal may be 15.140 Å, the lattice constant b may be 3.638 Å, the lattice constant c may be 9.190 Å, and the lattice constant β may be 101.1°.

The crystalline phase of the germanium-phosphide nanosheet may be a monoclinic crystal system crystalline phase.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타날 수 있다.In addition, when XRD analysis of the germanium phosphide (Germanium-Phosphide) nanosheet

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak may appear at 27.0° to 29.0°.

A space group of the germanium-phosphide nanosheet may be C2/m.

The lattice constant a of the Germanium-Phosphide nanosheet may be 15.140 Å, the lattice constant b may be 3.638 Å, the lattice constant c may be 9.190 Å, and the lattice constant β may be 101.1°.

The crystal phase of the germanium phosphide crystal and the crystal phase of the germanium phosphide nanosheet are monoclinic and represent the same crystal phase.

Then, using an anodized aluminum oxide (AAO) membrane to measure the band gaps of the germanium phosphide crystal and the germanium phosphide nanosheet, a bulk germanium phosphide thin film was placed on the surface of the anodized aluminum oxide (AAO) membrane. Alternatively, after forming the germanium phosphide nanosheet, a diffuse reflection spectrum is measured in absorption mode to measure the band gap of the germanium phosphide bulk thin film or germanium phosphide nanosheet.

First, the dispersion in which the germanium phosphide crystals are dispersed is dropped on the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 10 to 50 nm and applied, followed by vacuum drying to form a germanium phosphide (GeP) bulk thin film on the surface of the anode alumina. to form

Then, the band gap of the germanium phosphide (GeP) bulk thin film is measured by measuring the diffuse reflection spectrum in absorption mode with a UV-Vis-NIR spectrometer (Agilent Cary 5000).

Here, the band gap of the germanium phosphide bulk thin film is 0.5 to 0.9 eV (1380 to 2480 nm in terms of light wavelength), which is not in the visible-near-infrared region.

In addition, an anodized aluminum oxide (AAO) membrane is used to measure the band gap of the germanium phosphide nanosheet.

First, the upper layer liquid containing the exfoliated germanium phosphide nanosheet is dropped on the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 10 to 50 nm and applied, followed by vacuum drying to apply germanium phosphide (GeP) to the anode alumina surface. ) to form nanosheets.

Then, the band gap of the germanium phosphide (GeP) nanosheet is measured by measuring the diffuse reflection spectrum in absorption mode with a UV-Vis-NIR spectrometer (Agilent Cary 5000).

Here, the band gap of the germanium phosphide nino sheet is 0.92 to 2.5 eV (500 nm to 1350 nm in terms of light wavelength), indicating a band gap in the visible-near-infrared region.

1A is a schematic diagram of a melt growth method for synthesizing a germanium phosphide compound semiconductor crystal, which is a raw material of a germanium phosphide nanosheet according to an embodiment of the present invention, and FIG. 1B is a graph for the reaction conditions of the melt growth method.

1A and 1B, when synthesizing the germanium phosphide crystal, the germanium (Ge) powder and the phosphorus (P) powder are mixed in a molar ratio (Ge:P) of 1:5 to 5:1, and then a quartz ampoule A method of growing crystals by putting the quartz ampoule containing the reactant in a temperature-controlled electric furnace, sealing it in a vacuum, and melting it at a high temperature for a reaction temperature of 1000 to 1400 ° C and a reaction time of 12 to 64 hours (high temperature melting growth method), the synthesized germanium phosphide crystal can be synthesized in a pure state without impurities.

2 is a photograph of a crystal mass of a germanium phosphide compound semiconductor synthesized by a melt growth method according to an embodiment of the present invention.

As shown in FIG. 2 , the germanium phosphide compound crystal is obtained in the form of a black gray crystal mass.

In addition, the germanium phosphide crystal synthesized by the high-temperature melt growth method may be grown as a single-phase crystal.

In this case, the single-phase crystal phase of the germanium phosphide crystal may be a monoclinic crystal system crystal phase.

The synthesized germanium phosphide crystal is peeled off by any one or more of various mechanical peeling methods, that is, a mechanical peeling method including a scotch tape method, a poly(dimethylsiloxane), PDMS stamping method, or an ultrasonic grinding method using a solvent. Thus, a nanosheet having a thickness of 0.8 nm to 200 nm can be obtained.

However, the method of exfoliating the germanium phosphide crystal to form the germanium phosphide nanosheet is not limited to the mechanical exfoliation method.

3 is a schematic image of a process of manufacturing a germanium phosphide nanosheet by exfoliating a germanium phosphide compound semiconductor crystal mass according to an embodiment of the present invention by a mechanical method.

As shown in FIG. 3 , the bulk crystal, which is a crystal mass of the germanium phosphide compound semiconductor synthesized by the melt growth method, is ground to be pulverized into small crystals using a mortar or ball mill, and then the Scotch tape The germanium phosphide nanosheet may be formed by exfoliation by any one or more methods of legislation, a polydimethylsiloxane (PDMS) stamping method, or a mechanical exfoliation method including a solvent ultrasonic pulverization method.

However, the method of exfoliating the germanium phosphide crystal to form the germanium phosphide nanosheet is not limited to the mechanical exfoliation method.

In one embodiment, the ultrasonic pulverization method using a solvent, which is a liquid phase peeling method, is as follows.

The germanium phosphide crystals pulverized into the small crystals are added to an organic solvent, followed by ultrasonic reaction at a low temperature of 2 to 10° C. for 3 to 20 seconds using a high-density probe ultrasonic device, followed by a rest period of 2 to 5 seconds. It is exfoliated by ultrasonication for 5 hours. After the exfoliation, the solution is centrifuged at 2000 to 5000 rpm for 10 minutes to 1 hour to collect the liquid floating on the upper layer containing the exfoliated germanium phosphide nanosheets. After evaporating the organic solvent from the liquid floating on the upper layer, the germanium phosphide nanosheets having a long axis of 1 to 100 μm and a thickness of 0.8 to 200 nm are obtained in powder form.

4 is an X-ray diffraction (XRD, X-Ray Diffraction) pattern of a germanium phosphide nanosheet according to an embodiment of the present invention.

4 , the single-phase crystalline phase of the germanium phosphide nanosheet may be a monoclinic crystal system crystalline phase.

Here, both the germanium phosphide crystal and the germanium phosphide nanosheet may have the same monoclinic crystal phase.

If the crystalline phase of the germanium phosphide crystal is monoclinic, the crystalline phase of the germanium phosphide nanosheet may also be monoclinic when exfoliation is easily performed.

In addition, if the crystalline phase of the exfoliated germanium phosphide nanosheet is monoclinic, the crystalline phase of the germanium phosphide crystal may also be monoclinic.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타날 수 있다.Here, when XRD analysis of the germanium-phosphide nanosheet in the monoclinic crystal system

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak may appear at 27.0° to 29.0°.

The lower calculated value of FIG. 4 is a calculated XRD pattern of germanium phosphide (GeP) using the VESTA program (http://jp-minerals.org /vesta/en/), and the intermediate measured value of FIG. 4 is It is an XRD pattern of a germanium phosphide crystal, and the upper measurement value of FIG. 4 is an XRD pattern of a germanium phosphide nanosheet. The lattice constant of the calculated XRD pattern of germanium phosphide (GeP) (a = 15.140 Å, b = 3.638 Å, c = 9.190 Å, β = 101.1°) is the lattice constant of the measured XRD pattern of the synthesized germanium phosphide nanosheet ( a = 15.140 Å, b = 3.638 Å, c = 9.190 Å, β = 101.1°).

A space group of the germanium-phosphide nanosheet may be C2/m.

That is, the lattice constant a of the Germanium-Phosphide nanosheet in the monoclinic crystal system crystal phase is 15.140 Å, the lattice constant b is 3.638 Å, the lattice constant c is 9.190 Å, and the lattice constant β is may be 101.1°.

5A is an XRD diffraction pattern of a germanium phosphide-germanium mixed crystal according to a comparative example of the present invention, and FIG. 5B is an enlarged XRD diffraction pattern.

As shown in FIGS. 5A and 5B , the germanium phosphide-germanium mixed crystal synthesized at a reaction temperature of 930° C. during the melt growth method has a peak of germanium observed around 27.3° in the XRD pattern, so the germanium phosphide-germanium mixed crystal is phosphide. It can be confirmed that the germanium compound and residual germanium are mixed crystals.

6A is a schematic image of the crystal structure of a germanium phosphide nanosheet calculated in a ball-and-stick model according to an embodiment of the present invention, and FIGS. 6B and 6C are images according to an embodiment of the present invention A scanning electron microscope (SEM) image of a germanium phosphide nanosheet, FIGS. 6i and 6ii are a transmission electron microscope (TEM) image of a germanium phosphide nanosheet according to an embodiment of the present invention, and FIG. 6d is an energy-dispersive X-ray spectroscopy (EDX) element mapping result and element content analysis result of a germanium phosphide nanosheet according to an embodiment of the present invention.

정대축에서의 게르마늄(Ge) 원자와 인(P) 원자의 배열을 보여주었다.6A is a schematic image of the crystal structure of a germanium phosphide nanosheet having a Ge:P molar ratio of 1:1 calculated using a ball-and-stick model. As shown in FIG. 6a, the side view shows the arrangement of germanium (Ge) atoms and phosphorus (P) atoms in the [010] axis, and the front view is

The arrangement of germanium (Ge) atoms and phosphorus (P) atoms on the ordinate is shown.

Every germanium (Ge) atom is coordinated with three phosphorus (P) atoms and another germanium (Ge) atom, and every phosphorus (P) atom is coordinated with three germanium (Ge) atoms.

At this time, the monomolecular layers of each germanium phosphide nanosheet are stacked by van der Waals interaction to form a layered structure or a sheet structure spaced apart by 1 to 5 Å intervals.

That is, the germanium-phosphide nanosheet has a monolayer of a layered structure, and the interlayer distance of the monolayer may be 1 to 5 Å.

In addition, it can be confirmed from the scanning electron microscope (SEM) image of FIG. 6b that the germanium phosphide nanosheet has a structure in which thin plates are stacked on top of each other.

Here, the germanium-phosphide (Germanium-Phosphide) nanosheet may have a thickness of 0.8 nm to 200 nm. In addition, the germanium phosphide nanosheets having a structure in which thin plates are stacked are uniformly formed, so that the thickness of the germanium phosphide nanosheets can be increased from a few Å to a bulk size of several hundreds of μm.

In addition, the thickness of the germanium phosphide (Germanium-Phosphide) nanosheet may be preferably 0.8 nm to 150 nm, more preferably 1 nm to 100 nm, even more preferably 1 nm to 50 nm can be

면간거리

은 6.4 Å 임을 확인할 수 있다.And, from the scanning electron microscope (SEM) image of FIG. 6c and the transmission electron microscope (TEM) image and SAED dot pattern of FIGS. 6i and 6ii measured at a specific position (i or ii) on the SEM image, the germanium phosphide nanosheet is It is a single crystal, and the germanium-phosphide nanosheet has a monolayer of a layered structure, the interlayer distance of the monolayer is 1 to 5 Å, and the (204) interplanar distance d _{204 of the germanium-phosphide nanosheet.} is 2.1 Å,

face-to-face distance

It can be confirmed that is 6.4 Å.

In addition, from the EDX element mapping result of FIG. 6d , it can be confirmed that, in the germanium-phosphide nanosheet, a germanium (Ge) element and a phosphorus (P) element are evenly dispersed in the germanium phosphide nanosheet. And, from the EDX element content analysis result, it can be confirmed that the germanium (Ge) element and the phosphorus (P) element have a molar ratio (Ge:P) of 1:1 to constitute a germanium-phosphide nanosheet.

7 is a diffuse reflection spectrum in an absorption mode in which the band gap of a germanium phosphide crystal and a germanium phosphide nanosheet according to an embodiment of the present invention is measured.

In order to measure the band gap of the germanium phosphide crystal and the germanium phosphide nanosheet, an anodized aluminum oxide (AAO) membrane is used.

First, the dispersion in which the germanium phosphide crystals are dispersed is dropped on the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 20 nm and applied, followed by vacuum drying to form a germanium phosphide (GeP) bulk thin film on the surface of the anode alumina. .

Then, the band gap of the germanium phosphide (GeP) bulk thin film is measured by measuring the diffuse reflection spectrum in absorption mode with a UV-Vis-NIR spectrometer (Agilent Cary 5000).

Here, the band gap of the germanium phosphide bulk thin film is 0.9 eV (1380 nm when converted to a light wavelength), which is not in the visible-near-infrared region.

In addition, an anodized aluminum oxide (AAO) membrane is used to measure the band gap of the germanium phosphide nanosheet.

First, the upper layer liquid containing the exfoliated germanium phosphide nanosheet was dropped on the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 20 nm and applied, followed by vacuum drying to apply germanium phosphide (GeP) nanoparticles to the surface of the anode alumina. form a sheet

Then, the band gap of the germanium phosphide (GeP) nanosheet is measured by measuring the diffuse reflection spectrum in absorption mode with a UV-Vis-NIR spectrometer (Agilent Cary 5000).

Here, the band gap of the germanium phosphide thin film is 2.3 eV (540 nm in terms of light wavelength), indicating a band gap in the visible ray region.

Hereinafter, the present invention will be described in more detail through examples. It should not be construed that the scope of the present invention is limited by these examples.

<Example>

<Example 1> Preparation of Germanium-Phosphide (GeP) crystals

1a and 1b, germanium powder (purity 99.999%, manufacturer: Alpha-Acer) and phosphorus powder (purity 99.9%, manufacturer: Alpha-Acer) in a 1:1 molar ratio (Ge:P; 0.7 g: 0.3 g) After mixing, it was placed in a quartz ampoule and sealed under vacuum. The outer diameter of the quartz ampoule was 1 cm, the length was 2-3 cm, and the wall thickness was 2 mm. The quartz ampoule containing the mixed powder sample was placed inside an electric furnace capable of temperature control, and synthesized by a melt-growth method. The melt growth method synthesis conditions are described in Table 1 below. That is, the reaction temperature was slowly raised to 1100 °C over 24 hours according to the temperature increase condition of 44.8 °C/hr, reacted for 48 hours, and then slowly cooled to room temperature over 24 hours, as shown in FIG. -Phosphide, GeP) crystals were obtained.

GeP crystal synthesis conditions chemical formula Ge powder: P powder content temperature rise condition Reaction temperature (℃) Reaction time (hr) Cooling time (hr) GeP 0.7 g : 0.3 g 44.8 °C/hr 1100 48 24

<Example 2> Preparation of Germanium-Phosphide (GeP) nanosheets

As shown in the schematic image of the process of manufacturing the germanium phosphide nanosheet by exfoliating the germanium phosphide compound semiconductor crystal mass of FIG. 3 by a mechanical method, the bulk crystal which is the germanium phosphide compound semiconductor crystal mass synthesized by the melt growth method in Example 1 (bulk crystal) was ground using a mortar to grind into small crystals.

20 mg of the germanium phosphide crystals pulverized into small crystals were added to 10 mL of NMP (N-methyl-2-pyrrolidone, Sigma-Aldrich, anhydrous, 99.5%) as an organic solvent to prepare a solution in which germanium phosphide crystals were dispersed did Then, the reactor containing the solution was sonicated for 2 hours in a general ultrasonicator (Hwashin 605, 40 kHz, 350 W). It was then placed in a high-density probe ultrasonicator (Sonics VCX-130; 20 kHz, a maximum power output of 130 W) operating at 20% amplitude. The reactor containing the solution was placed in a water jacket connected to a circulator with a temperature controller, and the reactor temperature was maintained at 4°C. The ultrasonic tip of the high-density probe ultrasonicator was reacted for 10 seconds to prevent excessive heating, and the germanium phosphide crystal was peeled off using the high-density probe ultrasonicator for 2 hours in such a way that it had a break for 2 seconds. After the peeling was finished, the supernatant liquid containing the peeled germanium phosphide nanosheets was collected by centrifugation at 3000 rpm for 20 minutes. After evaporating the organic solvent from the upper liquid, germanium phosphide nanosheets having a long axis of 2 to 10 μm and a thickness of 1 to 30 nm were obtained in powder form.

<Example 3> Formation of a bulk thin film of germanium phosphide (GeP) on the surface of alumina anode

The dispersion in which the germanium phosphide crystals prepared in Example 1 are dispersed is dropped onto the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 20 nm and applied, followed by vacuum drying to form germanium phosphide (GeP) on the anode alumina surface. A bulk thin film was formed.

<Example 4> Formation of germanium phosphide (GeP) nanosheets on the surface of alumina anode

The upper layer liquid containing the exfoliated germanium phosphide nanosheets of Example 2 was dropped onto the surface of an anodized aluminum oxide (AAO) membrane having a pore size of 20 nm and applied, followed by vacuum drying and drying the germanium phosphide ( GeP) nanosheets were formed.

<Comparative Example 1> Preparation of germanium phosphide-germanium mixed crystal

A germanium phosphide-germanium mixed crystal was prepared by synthesizing in the same manner as in Example 1, except that the synthesis was performed at a reaction temperature of 930° C. during the melt growth method synthesis.

<Comparative Example 2> Preparation of germanium phosphide-germanium mixed nanosheets

A germanium phosphide-germanium mixed nanosheet was obtained by peeling in the same manner as in Example 2, except that the germanium phosphide-germanium mixed crystal of Comparative Example 1 was used.

<Experimental example>

UV-Vis-NIR spectrometer (Agilent Cary 5000), SEM (Hitachi S -4700), Pohang Radiation Accelerator XRD (9B beam line of the Pohang Light Source (PLS), or laboratory XRD (Rigaku D/MAX-2500 V/PC) using Cu Kα radiation (λ = 1.54056 Å), TEM (FEI TECNAI G2 200kV) and High-Voltage TEM HVEM (Jeol JEM ARM 1300S, 1.25 MV) were used.

<Experimental Example 1> Measurement of X-ray diffraction (XRD) pattern of germanium phosphide nanosheets

X-ray diffraction (XRD) patterns of the germanium phosphide crystals prepared in Example 1 and the germanium phosphide nanosheets prepared in Example 2 were measured.

4 is an XRD diffraction pattern of the germanium phosphide crystal prepared in Example 1 and the germanium phosphide nanosheet prepared in Example 2 above. In order to obtain an X-ray diffraction (XRD, X-Ray Diffraction) pattern of the germanium phosphide crystal of Example 1 and the germanium phosphide nanosheet of Example 2 of FIG. 4, Pohang Radiation Accelerator XRD (9B beam line of the Pohang Light Source) (PLS), or laboratory XRD (Rigaku D/MAX-2500 V/PC) using Cu Kα radiation (λ = 1.54056 Å) was used.

The lower calculated value of FIG. 4 is a calculated XRD pattern of germanium phosphide (GeP) using the VESTA program (http://jp-minerals.org /vesta/en/), and the intermediate measured value of FIG. 4 is It is the XRD pattern of the germanium phosphide crystal obtained in Example 1, and the upper measurement value in FIG. 4 is the XRD pattern of the germanium phosphide nanosheet obtained in Example 2. The lattice constant of the calculated XRD pattern of germanium phosphide (GeP) (a = 15.140 Å, b = 3.638 Å, c = 9.190 Å, β = 101.1°) is the lattice constant of the measured XRD pattern of the synthesized germanium phosphide nanosheet ( a = 15.140 Å, b = 3.638 Å, c = 9.190 Å, β = 101.1°).

From the XRD analysis, the crystalline phase of the germanium-phosphide crystal was a monoclinic crystal system.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타나고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타났다. Here, when XRD analysis of the germanium-phosphide crystal prepared in Example 1 of the monoclinic crystal system crystal phase

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak appeared at 27.0° to 29.0°.

And, the lattice constant a of the germanium-phosphide crystal prepared in Example 1 of the monoclinic crystal system crystal phase is 15.140 Å, the lattice constant b is 3.638 Å, and the lattice constant c is 9.190 Å. , and the lattice constant β was 101.1°.

In addition, from the XRD analysis, the crystalline phase of the germanium-phosphide nanosheet was a monoclinic crystal system crystalline phase.

피크의 회절각 2θ는 13.0°내지 15.0°에서 나타났고,

피크의 회절각 2θ는 27.0°내지 29.0°에서 나타났다.Here, when XRD analysis of the germanium-phosphide nanosheet prepared in Example 2 of the monoclinic crystal system crystal phase

The diffraction angle 2θ of the peak appeared at 13.0° to 15.0°,

The diffraction angle 2θ of the peak appeared at 27.0° to 29.0°.

A space group of the germanium-phosphide nanosheet was C2/m.

And, the lattice constant a of the germanium-phosphide nanosheet prepared in Example 2 of the monoclinic crystal system crystal phase is 15.140 Å, the lattice constant b is 3.638 Å, and the lattice constant c is 9.190 Å, and the lattice constant β was 101.1°.

The crystal phase of the germanium phosphide crystal prepared in Example 1 and the crystal phase of the germanium phosphide nanosheet prepared in Example 2 were monoclinic and exhibited the same crystal phase.

<Experimental Example 2> Measurement of X-ray diffraction (XRD) pattern of germanium phosphide-germanium mixed crystal

An X-ray diffraction (XRD) pattern of the germanium phosphide-germanium mixed crystal prepared in Comparative Example 1 was measured.

5A is an XRD diffraction pattern of the germanium phosphide-germanium mixed crystal prepared in Comparative Example 1, and FIG. 5B is an enlarged XRD diffraction pattern.

As shown in FIGS. 5A and 5B , in the XRD pattern of the germanium phosphide-germanium mixed crystal prepared in Comparative Example 1, a germanium peak was observed around 27.3°. Therefore, it was confirmed that the germanium phosphide-germanium mixed crystal prepared in Comparative Example 1 was a mixed crystal in which a germanium phosphide compound and residual germanium were mixed.

<Experimental Example 3> Modeling the atomic arrangement of germanium and phosphorus in germanium phosphide nanosheets

정대축에서의 게르마늄(Ge) 원자와 인(P) 원자의 배열을 보여주었다.6A is a schematic image of the crystal structure of a germanium phosphide nanosheet having a Ge:P molar ratio of 1:1 calculated using a ball-and-stick model. 6a, the side view shows the arrangement of germanium (Ge) atoms and phosphorus (P) atoms in the [010] axis, and the front view is

The arrangement of germanium (Ge) atoms and phosphorus (P) atoms on the ordinate is shown.

Every germanium (Ge) atom was coordinated with three phosphorus (P) atoms and another germanium (Ge) atom, and every phosphorus (P) atom was coordinated with three germanium (Ge) atoms.

<Experimental Example 4> SEM image measurement of germanium phosphide nanosheets

In order to know the shape of the germanium phosphide nanosheet prepared in Example 2, it was measured with a scanning electron microscope (SEM, equipment: Hitachi S-4700).

From the scanning electron microscope (SEM) image of FIG. 6B , it was confirmed that the germanium phosphide nanosheet prepared in Example 2 had a structure in which thin plates were stacked on top of each other.

The total thickness of the germanium-phosphide nanosheets having the structure in which the thin plates were stacked was 2 μm to 9 μm.

<Experimental Example 5> TEM image measurement of germanium phosphide nanosheets

In order to know the shape of the germanium phosphide nanosheet prepared in Example 2, it was measured with a transmission electron microscope (TEM, equipment: TEM (FEI TECNAI G2 200kV) and High-Voltage TEM HVEM (Jeol JEM ARM 1300S, 1.25 MV)). .

From the scanning electron microscope (SEM) image of FIG. 6c and the transmission electron microscope (TEM) image and SAED dot pattern of FIGS. 6i and 6ii measured at a specific position (i or ii) on the SEM image, it was confirmed that the germanium phosphide nanosheet was a single crystal. could check

Here, when the germanium-phosphide nanosheet is a single crystal, the electron beam is diffracted by a single crystal in a Fast Fourier Transform (FFT) image of a transmission electron microscope (TEM) and a Selected Area Electron Diffraction (SAED) pattern. It could be confirmed from what appeared to be separated into dots.

In addition, the monomolecular layers of each of the germanium phosphide nanosheets were stacked by van der Waals interaction to form a layered structure or a sheet structure spaced apart by 2 Å intervals.

The germanium-phosphide (Germanium-Phosphide) nanosheet had a monolayer of a layered structure, and the interlayer distance of the monolayer was 2 Å apart.

면간거리

은 6.4 Å 이라는 것을 확인할 수 있었다.And, the (204) interplanar distance d ₂₀₄ of the germanium phosphide (Germanium-Phosphide) nanosheet is 2.1 Å,

face-to-face distance

was confirmed to be 6.4 Å.

= 6.4 Å으로 문헌값(

= 6.367 Å)과 일치하는 것을 확인하였다.In the case of the lattice-resolution transmission electron microscope and Fast-Fourier Transform (FFT) analysis result (i), the [102] direction from the [201] normal axis is perpendicular to the [010] direction, and d ₂₀₄ = 2.1 Å. consistent with the value (d ₂₀₄ = 2.117 Å) and for (ii)

= 6.4 Å as the literature value (

= 6.367 Å) was confirmed.

In addition, the thickness of the germanium phosphide (Germanium-Phosphide) nanosheet in the TEM measurement was 2 nm to 20 nm.

<Experimental Example 6> Measurement of distribution and composition ratio of germanium and phosphorus elements in germanium phosphide nanosheets

In order to measure the distribution and composition ratio of the germanium element and phosphorus element in the germanium phosphide nanosheet, a high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) image, an EDX mapping image, and an EDX element content were analyzed.

6d is a high-angle annular dark field (HAADF) STEM (scanning transmission electron microscopy) image and an EDX mapping image to confirm that the germanium (Ge) element and the phosphorus (P) element are uniformly distributed throughout the germanium phosphide nanosheet. could

In addition, from the EDX element content analysis result, it was confirmed that the germanium (Ge) element and the phosphorus (P) element constitute a germanium-phosphide nanosheet in a molar ratio (Ge:P) of 1:1. As a result of the EDX spectrum analysis, it was confirmed that the ratio of the element germanium (Ge) to the element phosphorus (P) was 1:1.

<Experimental Example 7> Band gap measurement of germanium phosphide crystals and germanium phosphide nanosheets

7 is a diffuse reflection spectrum in an absorption mode in which the band gap of a germanium phosphide crystal and a germanium phosphide nanosheet according to an embodiment of the present invention is measured.

The band gap of the germanium phosphide bulk thin film formed on the surface of the anode alumina prepared in Example 3 and the germanium phosphide nanosheet formed on the surface of the anode alumina prepared in Example 4 was measured in both absorption and diffuse reflection spectra (measurement equipment: UV-Vis) -NIR spectrometer; Agilent Cary 5000).

7, the band gap of the germanium phosphide bulk thin film of Example 3 is 0.9 eV (1380 nm when converted to a light wavelength), and the band gap of the germanium phosphide nanosheet of Example 4 is 2.3 eV (at a light wavelength). 540 nm in terms of conversion).

Here, the band gap of the germanium phosphide nanosheet of Example 4 was 2.3 eV (540 nm in terms of light wavelength), indicating a band gap in the visible ray region.

As described above in detail a specific part of the content of the present invention, for those of ordinary skill in the art, it is clear that this specific description is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (17)

A germanium-phosphide nanosheet for an optoelectronic device having a band gap in the visible-near-infrared region. The method of claim 1,
The band gap of the germanium phosphide (Germanium-Phosphide) nanosheet is 0.92 eV to 2.5 eV, characterized in that
Germanium-Phosphide nanosheets. The method of claim 1,
The germanium phosphide (Germanium-Phosphide) nanosheet is characterized in that the molar ratio of germanium (Ge) to phosphorus (P) is 1:5 to 5:1
Germanium-Phosphide nanosheets. The method of claim 1,
The germanium phosphide (Germanium-Phosphide) nanosheet is characterized in that germanium (Ge) and phosphorus (P) are uniformly distributed in the nanosheet
Germanium-Phosphide nanosheets. The method of claim 1,
The crystalline phase of the germanium-phosphide nanosheet is a monoclinic crystal system, characterized in that
Germanium-Phosphide nanosheets. 6. The method of claim 5,
When XRD analysis of the germanium-phosphide nanosheet in the monoclinic crystal system

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak is characterized in that it appears at 27.0 ° to 29.0 °
Germanium-Phosphide nanosheets. 6. The method of claim 5,
The lattice constant a of the Germanium-Phosphide nanosheet on the monoclinic crystal system is 15.140 Å, the lattice constant b is 3.638 Å, the lattice constant c is 9.190 Å, and the lattice constant β is 101.1 ° characterized in that
Germanium-Phosphide nanosheets. The method of claim 1,
The space group (space group) of the germanium phosphide (Germanium-Phosphide) nanosheet is C2 / m characterized in that
Germanium-Phosphide nanosheets. The method of claim 1,
The germanium phosphide (Germanium-Phosphide) nanosheet, characterized in that the single crystal (single crystal)
Germanium-Phosphide nanosheets. The method of claim 1,
The germanium phosphide (Germanium-Phosphide) nanosheet has a monomolecular layer of a layered structure, characterized in that the interlayer distance of the monomolecular layer is 1 to 5 Å
Germanium-Phosphide nanosheets. The method of claim 1,
_{(204) interplanar distance d 204} of the germanium phosphide (Germanium-Phosphide) nanosheet is 2.1 Å,

face-to-face distance

characterized in that the silver is 6.4 Å
Germanium-Phosphide nanosheets. The method of claim 1,
The thickness of the germanium phosphide (Germanium-Phosphide) nanosheet is 0.8 nm to 200 nm, characterized in that
Germanium-Phosphide nanosheets. preparing a reactant by mixing germanium (Ge) powder and phosphorus (P) powder in a molar ratio (Ge:P) of 1:5 to 5:1;
putting the reactant in a quartz ampoule and sealing in a vacuum state;
Putting a quartz ampoule containing the reactant in a temperature-controlled electric furnace and synthesizing it by melting it at a high temperature for a reaction temperature of 1000 to 1400° C. and a reaction time of 12 to 64 hours to grow crystals to obtain germanium phosphide crystals;
exfoliating the germanium phosphide nanosheets by placing the germanium phosphide crystals in an organic solvent and ultrasonicating them intermittently for 1 to 5 hours at a temperature of 2 to 10° C. using an ultrasonic device; and
After centrifuging the peeled solution to collect the liquid in the upper layer, evaporating the organic solvent of the liquid to obtain a germanium phosphide nanosheet powder
Method for manufacturing germanium phosphide nanosheets. 14. The method of claim 13,
The crystalline phase of the germanium phosphide (Germanium-Phosphide) crystal is a monoclinic crystal system, characterized in that
Method for manufacturing germanium phosphide nanosheets. 14. The method of claim 13,
The crystalline phase of the germanium-phosphide nanosheet is a monoclinic crystal system, characterized in that
Method for manufacturing germanium phosphide nanosheets. 14. The method of claim 13,
When XRD analysis of the germanium-phosphide nanosheet

The diffraction angle 2θ of the peak appears at 13.0° to 15.0°,

The diffraction angle 2θ of the peak is characterized in that it appears at 27.0 ° to 29.0 °
Method for manufacturing germanium phosphide nanosheets. 14. The method of claim 13,
The lattice constant a of the Germanium-Phosphide nanosheet is 15.140 Å, the lattice constant b is 3.638 Å, the lattice constant c is 9.190 Å, and the lattice constant β is 101.1°
Method for manufacturing germanium phosphide nanosheets.

Images